Hi guys,

Since you are discussing the price of the 3D World MF viewer, I have to
tell you that the price of this viewer for me (buying in quantities, etc)
at some point (before the dollar weakened) was ONLY $11! (Shipping is a
big factor, adding a lot to the price, since they are shipping everything
Express Mail, but the viewer alone was $11).

I always wondered how is this possible? For $11 they are selling a viewer
with two fine coated achromatic lenses. And this leaves them a profit?
How much does the viewer actually cost to produce? $6? What is the cost
of each lens? $2?

This is just incredible...

I asked them to buy the lenses only, but at this point they had
discontinued the viewer (they made to special runs since then, one for me
and Dalia and one just for me) and did not want to sell the lenses only.

Now they are telling me that they will have the first production samples
of the new (focusing, lighted) viewer in a couple of weeks. I have a fear
that the lenses will not be achromatic... Let's hope for the best.

George

Hi George!

At 10:53 PM 7/28/2008, you wrote:

>How much does the viewer actually cost to produce? $6? What is the cost
>of each lens? $2?
>
>This is just incredible...

That is truly amazing!

>Now they are telling me that they will have the first production samples
>of the new (focusing, lighted) viewer in a couple of weeks.

Yay!! :-)

>I have a fear
>that the lenses will not be achromatic... Let's hope for the best.

Oh no!! :(

If they've shot themselves in the foot with something like PCX
lenses, our best hope for a commercially available, focusable,
handheld, backlit viewer with reasonably good performance will have
vanished (at least for the foreseeable future). I'm on pins and needles!

Is that just a hunch (the lack of achromatic doublets) or are your
concerns based on something they've actually communicated, such
as: "The lenses won't be as nice" or "We cut some corners on the
optics to keep the overall price down..."?

Thanks,

Mike Davis

> Is that just a hunch (the lack of achromatic doublets) or are your
> concerns based on something they've actually communicated, such
> as: "The lenses won't be as nice" or "We cut some corners on the
> optics to keep the overall price down..."?

Just a hunch. They said they are using different lenses than the ones in
the hand-held viewer. So, my first reaction was "why"? These lenses are
great, why change them? We'll soon know...

George

Hi Doc

> I always wondered how is this possible? For $11 they are selling a viewer
> with two fine coated achromatic lenses. And this leaves them a profit?
> How much does the viewer actually cost to produce? $6? What is the cost
> of each lens? $2?
>

Plenty of room in there for QC, agree?
:-) I agree Doc, 3dWorld is the best boom that ever happened to MF
stereo..... and I would guess the optics on their focusable viewer will
be the same, or an improvement, certainly not worse.

> Now they are telling me that they will have the first production samples
> of the new (focusing, lighted) viewer in a couple of weeks. I have a fear
> that the lenses will not be achromatic... Let's hope for the best.
>

yeah, really, keep us posted !!

Bill

George,

Thanks for the clarification.

I just went out to the 3DWorld web site and found some specs (in Chinese).

http://www.3dworld.cn/zh-cn/ProductDetails.aspx?productId=27

Using Babel Fish, I have very laboriously translated this page to English:

----

Hand-held Focusable 3D Viewer

Product model: 3DSHF120-1I

Product Characteristics:

1.  Adjustable focus.  This product replaces the fixed focus viewer to accommodate nearsightedness and people with presbyopia, satisfying the majority of viewers' needs.    (Presbyopia is the inability of older people to focus closely.)

2.  Built-in light source.  Usually the luminance is insufficient for viewing, seriously influencing the effect seen.  The lighting division has therefore designed a unit with enough brightness, even for use in total darkness.

3.  Low-consumption LEDs.  This product's lighting system is designed to work with provincial electricity or three 1.5V batteries which may provide continuous illumination for approximately 20 hours.  With intermittent service, this may lengthen for several lighting-up times, satisfying people's operation requirements completely.


Technical Parameters:

- Each eyepiece lens has 2 pieces of 2 groups, eliminating the chromatic dispersion, and eliminating the distortion characteristic.  

(I don't think they are saying these are four-element lenses.  This sounds like good old achromatic doublets to me.)

- Burnt Distance:   f=65mm     

(A 65mm focal length to cover 53mm mounts?  Interesting...)

- Focusing range: +/- 2.00 visual degrees   

(Huh?)

- Lighting source:  Via 20 high-luminance, wide color range, LEDs in conjunction with a high performance uniform light panel and diffuser, (***).     Color accuracy > or = 90%.

(OK, I deliberated for quite a while as to whether or not I should post this, but decided it wasn't sufficiently obscene to warrant omission, so here goes.  The English text that popped out of the Yahoo! Babel Fish translator at the location of the (***) string, as seen above, reads as follows:   "Leads the worn out fur woman with no pubic hair to be composed."   I'm not trying to be funny.  Seriously.  If you try translating the page yourself, that's what you'll get.  Surely that's not what 3DWorld was trying to say, but I've given up on trying to translate the translation the way I've done with the rest of this page.)

- Electricity Pond: Three 1.5V batteries.

- For use with Masks:  140mm (long) ×80mm (wide) ×3mm (thick)

- Picture size: 53mm×53mm (×2)

-----

It looks as if it could be a pretty good viewer, but I'm concerned about the lens diameters (too small?) and how close the diffuser appears to reside behind the film chips (will dust on the diffuser be visible when the film is in focus?)

Mike Davis

oooh! I just figured out how to see the larger image of the viewer.

Thanks Bob!

The characters in question, therefore translate to: "Composed of light
guide plates."

I suppose I should use Google for my Chinese-to-English translation needs
from now on.

This morning, without forewarning her of the Babel Fish translation, I
asked a co-worker who can read Chinese to translate those characters.
After a great deal of eyebrow scrunching, she told me that there's more
than one way to translate it, but given the technical context of the web
page, she concluded it means: "Composed of light reflection boards." I
asked her if she meant to say "mirrors" instead of "reflection boards" and
she said, "No, it's more like a conduit or pipe through which the light is
conducted."

Hmmm...

Mike Davis

On Tue, 29 Jul 2008, Bob Venezia wrote:

> This is how Google translates the same page (without me going the
> extra step of translating the translation). No mention of worn out
> fur women anywhere.
>
> Bob Venezia
>
> Features:
>
> 1. Are free to adjust the-horizon. This product subversion of the
> past fixed focal length-of-the-myopia, the old people can not see the
> flowers and other images of the defects, the most watched meet the
> demand.
>
> 2. Built-in light source. As usual places to watch the brightness
> is often inadequate, would seriously affect watch the results, so the
> lighting design part, even in the dark all circumstances, is of
> sufficient brightness.
>
> 3. Extremely low power consumption. This product of the lighting
> system designed by power-saving mode. 3 1.5 V batteries on the 5th
> of continuous lighting about 20 hours may be extended for several
> times when the use of intermittent lighting, to fully meet the
> requirements of the use of people.
>
> Technical parameters:
>
> Eyepiece: Each eyepiece two groups, with Consumers dispersion,
> Consumers distortion characteristics.
> f=65mm Focal length: f = 65mm
> Focus: +2.00 ~ -2.0 (as of)
> Lighting Source: from 20 high-brightness LED LED color gamut, with
> high-performance absorbed Guangmo, astigmatism film, composed of
> light guide plates. Reduction of ≥ 90%
> Battery: 3 on the 5th of 1.5 V battery.
> The use of film box: 140mm (length) × 80mm (width) × 3mm (D)
> Screen size: 53mm × 53mm (× 2)
>
> On Jul 29, 2008, at 1:37 AM, Michael K. Davis wrote:
>
> > George,
> >
> > Thanks for the clarification.
> >
> > I just went out to the 3DWorld web site and found some specs (in
> > Chinese).
> >
> > http://www.3dworld.cn/zh-cn/ProductDetails.aspx?productId=27
> >
> > Using Babel Fish, I have very laboriously translated this page to
> > English:
> >
> > ----
> >
> > Hand-held Focusable 3D Viewer
> >
> > Product model: 3DSHF120-1I
> >
> > Product Characteristics:
> >
> > 1. Adjustable focus. This product replaces the fixed focus viewer
> > to accommodate nearsightedness and people with presbyopia,
> > satisfying the majority of viewers' needs. (Presbyopia is the
> > inability of older people to focus closely.)
> >
> > 2. Built-in light source. Usually the luminance is insufficient
> > for viewing, seriously influencing the effect seen. The lighting
> > division has therefore designed a unit with enough brightness, even
> > for use in total darkness.
> >
> > 3. Low-consumption LEDs. This product's lighting system is
> > designed to work with provincial electricity or three 1.5V
> > batteries which may provide continuous illumination for
> > approximately 20 hours. With intermittent service, this may
> > lengthen for several lighting-up times, satisfying people's
> > operation requirements completely.
> >
> >
> > Technical Parameters:
> >
> > - Each eyepiece lens has 2 pieces of 2 groups, eliminating the
> > chromatic dispersion, and eliminating the distortion characteristic.
> >
> > (I don't think they are saying these are four-element lenses. This
> > sounds like good old achromatic doublets to me.)
> >
> > - Burnt Distance: f=65mm
> >
> > (A 65mm focal length to cover 53mm mounts? Interesting...)
> >
> > - Focusing range: +/- 2.00 visual degrees
> >
> > (Huh?)
> >
> > - Lighting source: Via 20 high-luminance, wide color range, LEDs
> > in conjunction with a high performance uniform light panel and
> > diffuser, (***). Color accuracy > or = 90%.
> >
> > (OK, I deliberated for quite a while as to whether or not I should
> > post this, but decided it wasn't sufficiently obscene to warrant
> > omission, so here goes. The English text that popped out of the
> > Yahoo! Babel Fish translator at the location of the (***) string,
> > as seen above, reads as follows: "Leads the worn out fur woman
> > with no pubic hair to be composed." I'm not trying to be funny.
> > Seriously. If you try translating the page yourself, that's what
> > you'll get. Surely that's not what 3DWorld was trying to say, but
> > I've given up on trying to translate the translation the way I've
> > done with the rest of this page.)
> >
> > - Electricity Pond: Three 1.5V batteries.
> >
> > - For use with Masks: 140mm (long) ×80mm (wide) ×3mm (thick)
> >
> > - Picture size: 53mm×53mm (×2)
> >
> > -----
> >
> > It looks as if it could be a pretty good viewer, but I'm concerned
> > about the lens diameters (too small?) and how close the diffuser
> > appears to reside behind the film chips (will dust on the diffuser
> > be visible when the film is in focus?)
> >
> > Mike Davis
>
>

- Each eyepiece lens has 2 pieces of 2 groups, eliminating the
chromatic dispersion, and eliminating the distortion characteristic.

(I don't think they are saying these are four-element lenses. This
sounds like good old achromatic doublets to me.)


No way, that means, two doublets, 4 elements total, this would be mandatory for 65mm fl. EXCELLENT!!! This viewer looks superb, and should be the missing link we have been waiting for! It almost appears as if there is an IPD adjust as well? See rings around the lenses on the viewer body? I am probably just fantasizing?

BTW, notice the IPD adjust in the enlarged image....

3 lines above the top of the barrel mount, when you twist the lens, it
will move l/r. If this represents 3mm - 4mm per eye, this will
accommodate close to a 58 - 72mm IPD, SUPERB!

I also suspect, that each eye is focusable individually, with the side
levers, if so, they hit a home-run with this viewer. I am sure it will
have VERY short ER, but assuming it has ind. eye focus, many EG wearers
can abandon their EG's when viewing. Very impressive... OK Doc, how
do we pre-order?

Wow! Thanks again, Bob.

On Tue, 29 Jul 2008, Bob Venezia wrote:

> oooh! I just figured out how to see the larger image of the viewer.
>
> http://tinyurl.com/5udrxf

I had tried to figure that out myself, clicking all over the page, without
success.

If the full-size drawing is accurate, it looks as if the viewer offers a
litte bit of interocular adjustment. Here comes a loaded question that
has several conditions:

IF we assume that the average person can not comfortably diverge their
eyes except for very short periods...

AND

IF we assume that the average stereographer will strive to limit on-film
deviation to something less than or equal to the viewer focal length
divided by 30 (MAOFD, which for this viewer will be 65mm/30 = 2.17mm)...

THEN

The lens spacing should not be user adjustable to distances less than
64.2mm (62mm window separation + MAOFD).

Which begs this question: Did 3DWorld limit the minimum lens spacing such
that divergence will be avoided for users that select the minimum lens
spacing when fusing Infinity homologs that have a 64.2mm separation, or
did they just provide an equidistant straddling of 65mm IPD spacing?

Which leads to this question: If your design can only serve some fraction
of that portion of the population that has IPDs ranging from 55mm to
75mm, for a viewer that will NOT have adjustable film chip spacing, do you
equip the viewer with interocular adjustments that straddle the 65mm peak
of the population bell curve (at the risk of forcing some users to diverge
their eyes on occaision) -OR- do you favor that portion of the population
with larger IPDs (to the right of center) so that no user whose IPD is
compatible with the viewer will have to suffer divergence?

I can't wait to find out how 3DWorld handled this. I suspect they just
straddled 65mm.

Mike Davis


On Tue, 29 Jul 2008, Bob Venezia wrote:

> oooh! I just figured out how to see the larger image of the viewer.
>
> http://tinyurl.com/5udrxf
>

Yes, it sounds interesting... I hope this turns out to be as good as you
are fantasizing it to be :)

I have placed an order for blank mounts and I asked them to include a
viewer if they have one ready to ship. I also asked them about the price.
I have not heard back yet, so I will let you know.

George

----- Original Message -----
From: "Bill G" <bglick@rconnects.com>
To: <MF3D-group@yahoogroups.com>
Sent: Tuesday, July 29, 2008 1:37 PM
Subject: Re: [MF3D-group] Specs for the new 3DWorld viewer (Was: Price of
the MF viewer)


> BTW, notice the IPD adjust in the enlarged image....
>
> 3 lines above the top of the barrel mount, when you twist the lens, it
> will move l/r. If this represents 3mm - 4mm per eye, this will
> accommodate close to a 58 - 72mm IPD, SUPERB!
>
> I also suspect, that each eye is focusable individually, with the side
> levers, if so, they hit a home-run with this viewer. I am sure it will
> have VERY short ER, but assuming it has ind. eye focus, many EG wearers
> can abandon their EG's when viewing. Very impressive... OK Doc, how
> do we pre-order?

> Which leads to this question: If your design can only serve some fraction
> of that portion of the population that has IPDs ranging from 55mm to
> 75mm, for a viewer that will NOT have adjustable film chip spacing, do you
> equip the viewer with interocular adjustments that straddle the 65mm peak
> of the population bell curve (at the risk of forcing some users to diverge
> their eyes on occaision) -OR- do you favor that portion of the population
> with larger IPDs (to the right of center) so that no user whose IPD is
> compatible with the viewer will have to suffer divergence?

Of course having the IPD spacing straddle the
mount apt. spacing makes the most sense. The answer to the IPD /
Divergence / Convergence with fixed mount spacing is a looooong story,
with lots of variables. I am burnt out, after typing my fingers to the
bones trying to explain why $10 lenses do not have enough budget for QC
- which we later found out from Dr. T, maybe there were $2 lenses?
And even then, I failed to get my point across - so I am having poor
success here, so I will be returning to lurker mode.


The short answer is, with 65mm fl lenses, and
relatively low light levels (which they will surely have) the problem of
divergence will rarely be an issue, except maybe for the 55+ crowd who
have very short IPD, maybe 59 mm or less.


However the benefits are HUGE, as I can assure
you these 4 elements lenses will be very sensitive to eye pupil / lens
center alignment. I am confident the reason IPD spacing adjustment was
provided was because the lenses would introduce way too much distortion
with even the smallest IPD / lens center spacing mismatch.... I am
talking +/- 1mm of range, maximum. This is why I could NOT make 4
element designs work to my satisfaction, but then again, I was using
shorter fl's.


If 3dworld lowered the fl's, in the 40 - 50mm
range, then I would not take this position....divergence would become an
annoying problem to a larger segment of the population. This is why
35mm viewers with the much shorter fl lenses suffer from greater levels
of divergence. (another feather in the cap for MF stereo) So, once
again, Kudos to 3d world for capitalizing on critical variables to serve
the masses....even if it happened to be by chance :-) I just
hope the lenses produce good enough MTF and minimal distortion... and
hopefully the ER will be no less than 15mm. I would prefer the ER to
be in the 20 - 22mm range, to service EG wearers with min. vignetting /
image clipping....but the lens diameters look much too small from the
picture to ever have long ER.

Bill

-

>Consumers distortion characteristics.
> f=65mm Focal length: f = 65mm
> Focus: +2.00 ~ -2.0 (as of)

No one seems concerned about 65mm FL? Seems to be a poor match for 80mm taking lenses in the camera. Could they be planning 65mm FL lenses on the camera? That would be nice.

Perhaps the "translation" got "Interocular" mixed up with "FL". (Stranger things have happened.) An interocular of 65mm with an adjustment of +2 or -2 could be understandable.

It is wait and see time.

Chuck Holzner




________________________________________________________________
Sent via the WebMail system at mail.firstva.com

Hi Chuck

>
> Perhaps the "translation" got "Interocular" mixed up with "FL". (Stranger things have happened.)

The reason they went to 4 elements, assuming
that interpretation was accurate, is because of reduced the fl.

Glad to learn that the 3D World focusing viewer is finally close to
availability. However, I am surprised that, if it really is within a
few days of being available, we still have not seen anything other
than CAD depictions of it !

The specs do sound amazing and the depiction does suggest interocular
adjustment and focusing. But one detail on the CAD drawing that does
worry me a bit is the closeness of the diffusion panel to the
transparency. The panel itself is also amazingly thin for something
that contains LEDs, which suggests the LEDs are extremely close to the
diffuser and that makes me wonder if the individual LEDs might not be
visible through the diffuser as a series of tiny hotspots.

Of course, we'll only know when we get to see and test an actual
sample...

So let's keep our fingers crossed !!!

Francois

--- In MF3D-group@yahoogroups.com, "Charles Holzner" <3D4me@...>
wrote:

>
>
> -
>
> >Consumers distortion characteristics.
> > f=65mm Focal length: f = 65mm
> > Focus: +2.00 ~ -2.0 (as of)
>
>
> No one seems concerned about 65mm FL? Seems to be a poor match

for 80mm taking lenses in the camera. Could they be planning 65mm
FL lenses on the camera? That would be nice.

>
> Perhaps the "translation" got "Interocular" mixed up with "FL".

(Stranger things have happened.) An interocular of 65mm with an
adjustment of +2 or -2 could be understandable.

>
> It is wait and see time.
>
> Chuck Holzner

I think you bring up a very good point. Either it is an error in
translation (65mm may be the interocular) or 3D World may be getting
ready to also introduce a new version of the camera with wider
optics ! That certainly would be answering what many have asked for.

Yes, very much "wait and see" and very exciting as well !

Problem is I am in a "can't wait" mood ! :-(

Francois

--- In MF3D-group@yahoogroups.com, "Bob Aldridge" wrote:

>
> I figured the illumination panel would be made like most flat

illuminators

> with the light source along the edge(s).
>
> The "magic" diffusion pattern printed on the panel would need to be
> carefully designed, of course, to even out the light, but computer

screens

> are now lit with LED illuminated panels, so it must be possible

(even though

> a computer screen is a far less critical project)...
>
> Bob Aldridge
>

Yes, of course that's a possibility. I was going by the LED panels
they put in their multi-slide viewers as well as in the original
mounting jig. Both of those have the LEDs behind and pointing
towards the transparency. However, in those instances, the LEDs are
much farther away from the film plane. It's possible that they are
using a completely different design along the lines you describe.

I am getting very impatient to see this viewer. But I still worry
about the proximity of the diffuser to the transparency...

Francois

>Both of those have the LEDs behind and

pointing

>towards the transparency. However, in those

instances, the LEDs are

>much farther away from the film plane. It's

possible that they are

>using a completely different design along the

lines you describe.


I seem to remember the first CAD "Pictures" of
the 3D World camera being somewhat different than
the final product.

Wait and see,

Chuck Holzner

Regarding- 2128.

For more than 50 years, in most instanced, we have been viewing 35mm
slides,in viewers that contained 44mm fl viewer lenses. The cameras
used were in, most cases, equipped with 35mm fl taking lenses

35mm/44mm equals a ratio of about .8.

If slides taken with the 3D World stereo camera are viewed in a 65mm
fl lensed viewer, the ratio, (65mm/80mm remains about the same, about .8.

I do not understand the basis for the, alleged, concern.

I believe that we should allow 3D World to do their thing without
having the MF3D members wringing their hands about the unknown.



DON

An obvious correction, My apologies.

35mm/ 44mm + .8. 80mm/65mm equals a ratio of abot about 1.2, not .8
as I mis-spoke. but in both cases, the degree of being non-ortho is
about the same. I don't remember hearing complaints about the
non-ortho problems caused by the non-ortho viewing of RBT slides when
they were taken with zoom taking lenses.


DON

Regarding 2121, a question was asked whether or not dust on the
diffuser will be be visible when the film is in focus ?

I do not recall ever being able to see dust on any light source that I
have seen in any 3D slide viewers. Certainly not on my panel light
which is positioned less than an inch from my film chips.

I fail to see a potential problem, with the position of the light
source on the, as of yet, un-seen 3D World viewer.

I trust 3D World to do the right thing.


DON

> Glad to learn that the 3D World focusing viewer is finally close to
> availability. However, I am surprised that, if it really is within a
> few days of being available, we still have not seen anything other
> than CAD depictions of it !

Who said "within few days"? It is a few weeks at best.

> 35mm/ 44mm + .8. 80mm/65mm equals a ratio of abot about 1.2, not .8
> as I mis-spoke. but in both cases, the degree of being non-ortho is
> about the same.

Yes, but in a different direction... I am sure this 65mm FL is wrong.
There is no logic behind this choice. Also, I seriously doubt that they
will have 2 achromatic lenses per eyepiece. Remember, they said that
this viewer will cost almost as much as the current hand-held viewer. $11
wholesale, $35 retail?

George

Also, I seriously doubt that they

> will have 2 achromatic lenses per eyepiece. Remember, they said that
> this viewer will cost almost as much as the current hand-held viewer. $11
> wholesale, $35 retail?

That's a big difference than what the
translators had to say :-) Maybe 3dWorld meant, the same cost as the
current mounting jig? That would make more sense, as these two products
are much closer.


As for viewer fl vs. taking fl.
IMO this is a non-issue. In theory there is compression / expansion on
the Z axis when using non-ortho taking / viewing fl's. However, I have
used viewing lenses that are .4 the taking lenses AND in the opposite
direction, I have used viewing lenses which are 2x the taking lenses
fl. In neither case is there any noticeable compression / expansion on
the Z-axis. When testing other people, they too could never see any
anomalies. Fortunately, our brains seem to be very forgiving in this
regard. Of course, this assumes near subjects are not abnormally
close to the camera. If the near subjects are too close, the problem
can be exasperated.

Bill

> Maybe 3dWorld meant, the same cost as the
> current mounting jig? That would make more sense, as these two products
> are much closer.

No, they made this perfectly clear, and the communications were via a
person who speaks (writes/communicates) perfectly in English. They said
that they are discontinuing the current hand-held viewer because the new
viewer will be much better and will cost about the same, so there is no
reason to have two products at the same price range, one being better than
the other. So I expect the new viewer to retail between $35 to $50 (just
my guess and expectation from what they said - of course, things can
change when the viewer is finally produced and all the costs are known.)

> I have
> used viewing lenses that are .4 the taking lenses AND in the opposite
> direction, I have used viewing lenses which are 2x the taking lenses
> fl. In neither case is there any noticeable compression / expansion on
> the Z-axis. When testing other people, they too could never see any
> anomalies. Fortunately, our brains seem to be very forgiving in this
> regard.

I don't know Bill... Yes, the brain is both forgiving and also adapting
(i.e. adapts quickly to new viewing conditions) but I can
see/sense/observe a difference when I switch lenses from 45mm to 50mm in
my Combi 35mm viewer. Switching lenses from 30 to say 80mm in this viewer
(if they were available) would make a world of difference to me. I am
really surprised to hear you say this large change in viewing lens FL does
not cause noticeable effects.

George

Hi George,

On Wed, 30 Jul 2008, DrT (George Themelis) wrote:

> I don't know Bill... Yes, the brain is both forgiving and also adapting
> (i.e. adapts quickly to new viewing conditions) but I can
> see/sense/observe a difference when I switch lenses from 45mm to 50mm in
> my Combi 35mm viewer. Switching lenses from 30 to say 80mm in this viewer
> (if they were available) would make a world of difference to me. I am
> really surprised to hear you say this large change in viewing lens FL does
> not cause noticeable effects.

Bill will surely respond to your comment himself, but I think you'll find
that he wasn't discounting any of the observed differences that come with
changing viewer focal lengths *other than* the compression or expansion of
the z-axis, and I'd have to agree with my interpretation of what he's
saying in that regard. Certainly, there can be a dramatic change in
magnfication, for example, but the change in perspective is subtle - it
doesn't feel nearly as dramatic, and thus, is not worthy of too much
concern.

I think we don't have to worry about compression or expansion because
everyone is used to looking at 2D prints at many distances other than
their ideal viewing distances. Ideally, all 2D prints should be viewed at
a distance equal to the focal length of the taking lens multiplied by the
enlargement factor required to produce the print. In practice, we hit
that ideal viewing distance only accidentally, and thus, we've been
heavily conditioned to have no expectation of viewing images at the
ideal distance.

When you weigh this against the tremendous gain in immersion that can come
with increasing the magnification of a viewer, a little bit of z-axis
compression is well worth the price, in my opinion.

For those who choose to shoot with variable-base rigs, any mismatch in
viewer focal length vs. taking focal length can also be compensated by
calculating a stereo base that takes this into account. There are many
limitations that come with variable-base rigs, of course, but I'll leave
that for another thread. Hint: Don't bother telling me that fixed-base
(65mm) stereo cameras can produce superior results under many
cirumstances. I know they can.

Thanks,

Mike Davis

> Certainly, there can be a dramatic change in
> magnfication, for example, but the change in perspective is subtle - it
> doesn't feel nearly as dramatic, and thus, is not worthy of too much
> concern.

I agree, to a point. When I first looked a 35mm stereo slide with 35mm
lenses, I was struck by the compression effect on a slide I was used to
viewing with 44mm lenses (to be more accurate, the 35mm viewing lenses
gave a correct perspective since the picture was recorded with 35mm
lenses, so a better way to say this is that what impressed me was the
"lack of expansion" I was used to seeing with my regular viewer.)

Also, when I first saw a "portrait" (people standing at 5 feet from the
camera) projected, I was appalled by the stretch I was experiencing.
Totally unflattering for the faces. I was projecting with 5" lenses so I
was getting the equivalent perspective of viewing the picture with 125mm
lenses. With time I got used to this "projection stretch" and now I don't
notice it. A lot of what we "see" is related to comparing to what we are
used to seeing. The brain adapts...

People exposed in stereo projection for the first time also comment on
this "stretch" seen in projection of familiar subjects like people/faces.
They also comment on people looking like statues and the un-reality of
"frozen" action. Or the miniaturization/gigantism effect of hyper/hypo
stereo. These observations are a good sign because they imply that the
observer is comparing the stereo image with reality, so he/she is
impressed by the realism of the stereo image. With more exposure to
stereo photography, one does not notice these things. We are getting used
to seeing stereo images and we tend to accept (or be less impressed by)
any deviations from reality.

> I think we don't have to worry about compression or expansion because
> everyone is used to looking at 2D prints at many distances other than
> their ideal viewing distances. Ideally, all 2D prints should be viewed
> at
> a distance equal to the focal length of the taking lens multiplied by
> the
> enlargement factor required to produce the print. In practice, we hit
> that ideal viewing distance only accidentally, and thus, we've been
> heavily conditioned to have no expectation of viewing images at the
> ideal distance.

I agree (to a certain degree :))

> When you weigh this against the tremendous gain in immersion that can
> come
> with increasing the magnification of a viewer, a little bit of z-axis
> compression is well worth the price, in my opinion.

Maybe :) I think I would still prefer to be as close to ortho as
possible.

George

> No, they made this perfectly clear, and the communications were via a
> person who speaks (writes/communicates) perfectly in English. They said
> that they are discontinuing the current hand-held viewer because the new
> viewer will be much better and will cost about the same, so there is no
> reason to have two products at the same price range, one being better than
> the other. So I expect the new viewer to retail between $35 to $50 (just
> my guess and expectation from what they said - of course, things can
> change when the viewer is finally produced and all the costs are known.)
>

Wow, hard to believe the mounting jig
which is a doublet version of this new viewer sold for $150+ retail and
now this viewer will sell for $40? I realize this is all speculation
at this point...so keep us posted....

> Switching lenses from 30 to say 80mm in this viewer (if they were available) would make a world of difference to me.

Can you describe what the "world of
difference" you see? I have never noticed this in my Combi viewer.

> I am really surprised to hear you say this large change in viewing lens FL does
> not cause noticeable effects.
>

To be more specific... when I change viewer
fl's with the same film being viewed, yes, I see a different look, as
the fl's are different. However, I don't see any oddities on the
Z-axis, which is what I was referring to. The way this plays out in
real world viewing is.... you use one fl viewing lens, and then view
slides shot with all different taking fl's. In this regard, I have
never seen any Z-axis effects. The only time I ever saw a noticeable
Z-axis expansion was with a subject within 4ft of the camera, which was
in violation of the total deviation I was shooting for.


I am curious what your experiences are, as 35mm has a wider range of
taking lenses.


Bill

> I think we don't have to worry about compression or expansion because
> everyone is used to looking at 2D prints at many distances other than
> their ideal viewing distances. Ideally, all 2D prints should be viewed at
> a distance equal to the focal length of the taking lens multiplied by the
> enlargement factor required to produce the print. In practice, we hit
> that ideal viewing distance only accidentally, and thus, we've been
> heavily conditioned to have no expectation of viewing images at the
> ideal distance.
>

This is the PERFECT and "almost" EQUAL analogy
which we are confronted with on a regular basis..... just think how
large a given fl range is on a zoom lens, often 300% zoom range? Yet
whether we capture at ultra wide angle, or long tele's, we always view
them at the same distance. We never try to purposely adjust the view
distance to correct for perspective.


Granted, they are not in stereo, so to level the playing field, use
only one eye to view. With one eye, the capture and viewing parameters
are equal. Since only about 1/3 of our sense of depth comes from
deviation, this experiment should yield some quirks....yet, I have never
experienced it, and never noticed it with others. To be fair though,
it's possible to push this mismatch further in film based stereo capture
and the different viewing methods, specially projection.....as in all
forms of stereo, we do add the deviation to the list of variables. But
this 2d analogy is a strong indicator that our brains have a lot of
flexibility in capture distances vs. viewing distances.


Also, in stereo viewing, we have other variables that trick the brain,
such as divergence, excess convergence, hyper, hypos, etc.... I
imagine the right recipe of errors (vs. normal vision) can create a
witches brew of oddities when viewing at different distances (fl's).
So to clarify, my point is....when shooting "normal" based stereo
cameras, while keeping the nears at distance which will NOT violate your
max. subject deviation, the brain allows a very wide range of view lens
fl vs. capture fl. I am still comfortable with view lenses fl's at
.4x to 2x capture fl's. I have even seen a lot at 3x also, and still
no problems...but I have not shown the 3x to enough people yet, to feel
as confident including it.


When discussing stereo capture / viewing, there really is a slew of
variables, therefore, I should have been more specific of exactly what i
was presenting, so thanks for pushing this a bit further.


Stereo projection really adds to the list of variables. As only one
row of seats will be viewing at the "ideal" distances (preferably the
middle row). The distance between the front and back rows can add
very large variances to the view distance, much greater than what we are
discussing for viewing film in conventional optical stereo viewers.
Since I never project, I overlooked mentioning this qualifier.

Oops !!! Looks like I started another big debate ! Sorry about
that folks !!!

All I meant to do is try to theorize on why they would have chosen a
shorter focal lenght on the viewer lenses, also taking into
consideration the fact that I know Sam discussed the possibility of
a WA camera with 3D World and 3D World DOES listen to input from
users. Why do you think they have decided to go ahead and design a
focusing illuminated viewer ? Likewise, the choice of the viewer
lenses may have been motivated by the eventuality of a WA camera.

Of course, that is based on the assumption that the 65mm mentioned
does refer to focal length and even that is questionable.

Everything else is just theorizing by all of us at this point, based
on a (most likely outdated) CAD drawing and some poorly translated
specs.

Yes, it would be fantastic if this were a 4-element lens WA viewer.
I think we all agree on that ! But maybe we should take the
opposite approach. Let's expect a really crappy viewer and then be
real surprised with whatever it turns out to be !

I think right now we may be setting ourselves up for a letdown if we
all assume that this viewer is going to match all our idealistic
expectations.

I would also like to point out that this viewer was to be available
several months ago. 3D World ceased production of the simple viewer
at that point, expecting to replace it with the new viewer. But we
heard that the head of 3D World was not happy with the new viewer
and it got redesigned. The CAD drawings we have seen so far all
appear to be of the old design. So the actual one that comes out
may be different - or not !

One thing for sure: If this new viewer is as low-cost as Dr.T
claims, it's hard to believe it will offer all that we would like.
Maybe the lenses will be plastic ! So let's not get over-
enthusiastic...

I think I'll change my closing statement to...
"I'll believe it when I see it !"

Francois

I suspect that the second guessing that led to the 4 element lenses may have been optimistic.

 

I think the specs said something like 2 x 2 elements didn't they? So that's two lenses (one for each eye) and each of them is two element, surely?

 

With 3DWorld's economical approach I think they're much more likely to keep the price down at adequate quality rather than ruin the sales for a relatively small increase in optical quality...

 

Bob Aldridge

---

From: MF3D-group@yahoogro ups.com [mailto:MF3D- group@yahoogroup s.com] On Behalf Of depthcam
Sent: 30 July 2008 20:26
To: MF3D-group@yahoogro ups.com
Subject: [MF3D-group] Re: Specs for the new 3DWorld viewer

Yes, it would be fantastic if this were a 4-element lens WA viewer.
I think we all agree on that ! But maybe we should take the
opposite approach.

.

--- In MF3D-group@yahoogroups.com, "Bob Schlesinger" wrote:

>
> Well, I agree with others that have said we are all just

speculating (and drooling) at this point, however Google Translate
gives the following from their website:

>
> "Eyepiece: Each eyepiece two groups, with Consumers dispersion,

Consumers distortion characteristics."

>
> It says that EACH has two GROUPS so one could surmise 4 elements

for each.

> Are there any Chinese literate members of MF3D ? Is there any

potential confusion in translation between the word "group" and lens
element ?

>
> Now if it also got rid of "consumer dispersion" and "consumer

distortion", they'd REALLY have a breakthrough :-)

>
> Bob Schlesinger

I think the assumption that they are indeed two GROUPS of lenses is
based on a legitimate interpretation of the specs. And the
assumption that it is a WA viewer is likewise legitimate.

The problem is it all sounds TOO GOOD to be true ! It might make
sense if the price of the new viewer were on par with the mounting
jig or in between the simple viewer and the mounting jig. But if
there was no communication error between Dr T and his Chinese
correspondent, how could such a substantially more sophisticated
viewer be sold at the same price as the simple version ?

That's why it may be more cautious not to expect much until someone
here gets to inspect an actual one...

Francois

> It says that EACH has two GROUPS so one could surmise 4 elements for
> each.
> Are there any Chinese literate members of MF3D ? Is there any
> potential confusion in translation between the word "group" and lens
> element ?

I am sure there is :)

Does the group always has two elements? There might be even more lenses,
like 6 elements in 2 groups :)

George

--- In MF3D-group@yahoogroups.com, "DrT \(George Themelis\)" 3d@...> wrote:

> Who said "within few days"? It is a few weeks at best.
>

In post 2126:
"I have placed an order for blank mounts and I asked them to include a
viewer if they have one ready to ship"


That made it sound to me like the viewer is just about ready to ship...

Francois

Oh, yes, there are all kinds of possibilities.........
Maybe the Chinese government has secretly decided to subsidize the development of high quality optics - so maybe they get the lenses for free, or the government pays them for
each lens element they sell :-)

Bob

>*********** REPLY SEPARATOR ***********

>
>Does the group always has two elements? There might be even more lenses,
>like 6 elements in 2 groups :)
>
>George
>
>

--- In MF3D-group@yahoogroups.com, "Bob Schlesinger" wrote:

>
> Oh, yes, there are all kinds of possibilities.........
> Maybe the Chinese government has secretly decided to subsidize the

development of high quality optics - so maybe they get the lenses for
free, or the government pays them for

> each lens element they sell :-)
>
> Bob

Or maybe the whole specs sheet is a piece of disinformation. At this
very moment they are laughing at our pitiful attempts at translating
the nonsense and our wild theories about it. They really had a good
laugh about that furry thing that babelfish found ! That was probably
an accurate translation. They just put that in there to mess with our
minds.

Francois

> Does the group always has two elements? There might be even more lenses,
> like 6 elements in 2 groups :)

hey Doc, c'mon, stop teasin us :-)

Next you may tell us this entire gig was nothing but a rouse. hee hee

In 2140,

I have used viewing lenses that are .4x taking lenses and in the
opposite direction, I have used viewing lenses which are 2X taking
lenses. In neither case is there any noticeable compression/expansion
on the Z axis.

No mention was made as to what the fl of the normal lens was, but if
it were 35mm fl, .4X and 2X would indicate the lenses were 14mm fl and
70mm fl, respectively. I have a difficult time understanding why NO
noticeable compression or expansion was seen on the Z axis, if these
were the lenses which were used.


DON

Hi Bob and Francois,

On Wed, 30 Jul 2008, depthcam wrote:

> --- In MF3D-group@yahoogroups.com, "Bob Schlesinger" wrote:
> >
> > Oh, yes, there are all kinds of possibilities.........
> > Maybe the Chinese government has secretly decided to subsidize the
> development of high quality optics - so maybe they get the lenses for
> free, or the government pays them for
> > each lens element they sell :-)
> >
> > Bob
>
>
> Or maybe the whole specs sheet is a piece of disinformation. At this
> very moment they are laughing at our pitiful attempts at translating
> the nonsense and our wild theories about it. They really had a good
> laugh about that furry thing that babelfish found ! That was probably
> an accurate translation. They just put that in there to mess with our
> minds.
>
> Francois

Thank you for introducing some humor into this thread! :-)

But I'd like to fuel the speculation just a little bit more, by sharing
that I just asked my Chinese co-worker to have another look at the group
of 10 characters that start the line of text just above "f=65mm" on
this page:

http://www.3dworld.cn/zh-cn/ProductDetails.aspx?productId=27

She says:

The two characters that begin the line, to the left of the colon, mean:

Eyepiece:

The first two characters following the colon mean:

Each

The next two characters are the SAME as those to the left of the colon:

Eyepiece

The next two characters mean: 2 slices

(She emphasized that this character refers to a flat slice of something or
a flat piece of something - as you would say when refering to a piece of
paper - something planar - her words.)

The last two characters mean: 2 groups

So here it is in total, just as she translated it:

Eyepiece: Each eyepiece 2 slices 2 groups.

She says that any Chinese person who can read Chinese would get exactly
that out of it and nothing more, so we have to make of it what we can.

Does that mean 2 elements in each of two groups? One element in each of
two groups? About the only thing we can say for sure about this line of
text (if not the actual viewer) is that each eyepiece has TWO GROUPS, and
that automatically means it's NOT an achromatic doublet. Hmmmmm...

When I asked her if she thinks it means a total of 4 slices, two slices in
each of two groups, she said, "It doesn't say enough for me to answer your
question. It just says 'two slices, two groups', but I'm sure there are
at least two groups and at least two pieces." I didn't bother to explain
how an optics group can have either one element or multiple elements, etc.
She's just telling me what the Chinese characters say.

About the only thing we can say for sure about this line of text (if not
the actual viewer) is that each eyepiece has TWO GROUPS, and I think that
automatically means it's not an achromatic doublet, because a double is
always described as a single group, right?

Arrrgh! We'll have to wait and see, but it's still fun to speculate.
We'll probably learn that this web page is thoroughly innacurate. And
yes, if they are reading our posts, they must be enjoying the show.

:-)

Mike Davis

Bill,

I strongly disagree with the “1/3 of our sense of depth comes from
deviation,” at least if I understand what you are saying.

ALL of our sense of STEREO depth comes from deviation.

Every one of the 2D clues to depth can be trumped by stereo deviation.
Witness psuedo views. Not to say 2D clues can’t add tremendously to a 3D
view or confuse a psuedo view. And they are all ya’ got in 2D.

The brain, indeed, can compensate for lots of differences from “ortho”
stereo presentation. It doesn’t have anything to do with film-based or other
methods or viewing methods.

Yes, our brains DO a marvelous job of compensation in many ways. For instance, though
doubling stereo base when doubling focal length helps the brain interpret
the illusion, it doesn’t make it the “same” as an ortho-stereoscopic view.

Different people’s brain-visual systems can tolerate a lot of difference
between ortho and, for instance, hyper, hypo, pepax, macro, etc. And even
when the differences are seen, the result can be pleasing and enjoyable.

The deformation of the z-axis is one of those things that is unremarkable to
a lot of folks especially in stretch versus squash.

LeRoy

On 7/30/08 11:42 AM, "Bill G" wrote:

Since only about 1/3 of our sense of depth comes from deviation, this
experiment should yield some quirks....yet, I have never experienced it, and
never noticed it with others.   To be fair though, it's possible to push
this mismatch further in film based stereo capture and the different viewing
methods, specially projection.....as in all forms of stereo, we do add the
deviation to the list of variables.   But this 2d analogy is a strong
indicator that our brains have a lot of flexibility in capture distances vs.
viewing distances.

On 2134,

It will be quite hard to stop specs of dust from marring the view,
specially as the diffuser will probably be made of acrylic plastic
which soon gets a static charge.

I fail to see the, alleged, problem, as most slides film chips have
many specs of dust on their outer surface.

How is it possible that the dust, which is behind the slide, on the
diffuser, is able to mar the view, when most of the dust specs on the
slide are not visible, and even though they are in front of the diffuser ?

DON

Hopefully, the new viewer does have a pair of achromats in each
eye-piece. Paired achromats may be designed to reduce distortin
problems and can increase significantly, the amount of eye-relief,
which will help those that wear eye-glasses.

DON

> Also, when I first saw a "portrait" (people standing at 5 feet from the
> camera) projected, I was appalled by the stretch I was experiencing.
> Totally unflattering for the faces. I was projecting with 5" lenses so I
> was getting the equivalent perspective of viewing the picture with 125mm
> lenses.

Hey Doc, I am not a projection expert, so
I am sure others can ring in here too....but IMO, the perspective issue
for projection viewing is not a function of the projectors fl. Here is
why.... a good analogy I can offer is a dark-room enlarger. Example,
you make two 12" square prints from 6x6 film, one with a 60mm fl and the
other with a 120mm fl enlarging lens. When you view both prints side
by side, it would be impossible to distinguish them apart regardless of
the view distance. Hence why a lenses fl in projection is not relevant
for perspective issues.


All that matters in any non optical based stereo viewing, mainly
projection and lensless viewers (Mirscope) is, the final image diag. vs.
the view distance. If these two equal, and the capture lens fl and the
film format were equal, you are viewing in ortho. The projection lens
fl does not come into play. The projection lens fl only dictates the
screen to projector distance required for a desired size final projected
image.



This all can be confusing as we are trying
to combine both capture variables with viewing variables. It's a
hodge podge of variables, which often get changed after the initial
capture. Which was partly how this thread went off onto a tangent.
On the capture side, we have lens fl's, film formats, digital sensor
formats combined with their potential enlargements (Mirscope, Holmes, PC
viewing, projection, etc), vs. the non enlarged film based viewers -
(camera film direct to viewer). On the viewing side, we have optics
based viewers and their fl's, non optics viewers / projection, with
their associated view distances.


Hence why I prefer to simplify all the variables, and have them all
funneled to one common denominator that joins capture and viewing
variables, as it relates to perspective..... here is my method....


The net effect of all these capture / viewing variables is what I call
"perspective factor" or PF.

PF = CPF * VF


CPF = Capture Perspective Factor = capture lens fl / capture media diag.
(1= Normal CPF, <1 = Wide angle CPF, >1 = long CPF)


VF = Viewing Factor = Final Image size diag. / View distance.
(1=Normal VF, 53 deg AFOV, <1=WA VF, >1=tele VF)



When PF = 1, you have Normal viewing Perspective Factor, however, a
distinction should be made....


True Ortho viewing only takes place when CPF and VF = 1. Other
combinations which create PF = 1, are considered "corrected
perspective", a slight distinction as the final views under these two
scenarios are not EXACTLY the same. But when using reasonable
variables as I stated earlier, the brain is very forgiving in this area
and most often the slight differences are not discernible.
However, if you push the variables far enough, you can create visual
oddities on the Z - axis, however, with the lens fl's and view methods
we work with, this is not a big issue IMO. The only realistic
exceptions are:


1) having subjects too close, and


2) the use of projection which has potential for larger errors as final
image size can easily be manipulated. I think Doc's projection example
was probably a witches brew of these two. This PF formula, is NOT
applicable for macro or close-up work.


Anyway, the reason I use this simple method is, it provides me a common
denominator to evaluate all the possible capture and viewing
variables. It doesn't matter if you shoot stereo with 8x10 film or
digicams (or anything in between), or whether you view the images with
lensless viewers, optics based viewers or projection, when PF values
match, you will perceive the exact same perspective.


To be clear though, equal PF does not equate to the same viewing
experience. Often the viewing experience is a function of VF (View
Factor). VF by itself, is not about perspective. It's is about AFOV,
or the immersion (IMAX) factor.... which is part of the Holy Grail John
Hart mentioned, also referred to as WOW factor.... so I have provided a
few simple references to give users a feel for the potential immersive
effect based on VF....


VF =

.3 = ViewMaster Kiddie viewers, 18 deg AFOV (diag)
.8 = 35mm stereo, using 24x30 film w/ 50mm lens, 42 AFOV
1.0 = 3DWorld viewer, 52 deg. AFOV (a standard for many optics)
1.3 = Ultra Wide 35mm, w 30mm fl, 24x30 film, 65 deg AFOV.
1.7 = Ultra Wide MF viewer, 44mm FL, 80 deg AFOV
2.0 = IMAX's newest 3d theaters, middle row, 90 deg. AFOV
2.2 = Human eye, max. AFOV per eye, 95 deg. AFOV.



So while true ortho is not always possible,
or desirable, with this simple approach the user can easily determine
how the perspective of his capture / viewing systems compares with a
Normal Perspective (PF = 1.0), or how it compares with other capture /
viewing methods.


Also View Factors "Final Image Size"
assumes a non cropped version of the original image. Enlarging the
original capture is OK, hence the term "Final" Image size.


Anyway, its too bad our stereo forefathers
never provided a simplified method like this, to boil down all the
variables to a few common denominators. Then again, they never had so
many capture and viewing methods available to them. It would surely
simplify the process of trying to compare all the different capture /
viewing methods.... Maybe some of the stereo organization executives
will spear head a movement to bring some standardized verbiage like
this.......it sure would avoid a lot of confusion...


Bill

Hi Don!

> No mention was made as to what the fl of the normal lens was, but if
> it were 35mm fl, .4X and 2X would indicate the lenses were 14mm fl and
> 70mm fl, respectively. I have a difficult time understanding why NO
> noticeable compression or expansion was seen on the Z axis, if these
> were the lenses which were used.
>

In this case, it was MF.... but some
of the later posts should offer additional insights by others ...

>
> DON
>
>
>

> About the only thing we can say for sure about this line of text (if not
> the actual viewer) is that each eyepiece has TWO GROUPS, and I think that
> automatically means it's not an achromatic doublet, because a double is
> always described as a single group, right?

Yep, you got that right.....and, if
the fl is right at 65mm, which it appears like such in the solid model,
(assuming its scaled properly) than most likely it will have to contain
4 elements per eye, as 3 elements would not control distortion well
enough.... If 3d world is watching this thread, they must get a good
laugh at us Americans :-)

Hi Leroy

>
> I strongly disagree with the ³1/3 of our sense of depth comes from
> deviation,² at least if I understand what you are saying.
>
> ALL of our sense of STEREO depth comes from deviation.
>

The military has done some extensive
testing in this area, as well as lots of optical researchers.... it came
as a surprise to me as well.... IIRC, one text I read stated deviation
representing as low as 25% of our total depth cues. As an interesting
experiment, cover one eye and look at an area that you have never seen
before, and see if you can place all the subjects in depth order.... I
did this several years ago, and remarkably, I could place the depth of
objects as well with one eye as I could two, except maybe when they got
really far, say 70ft+. So, I became a believer....

> Hey Doc, I am not a projection expert, so
> I am sure others can ring in here too....but IMO, the perspective issue
> for projection viewing is not a function of the projectors fl.

Yes, I should have clarified that I am the projectionist and I am standing
by the projector, in which case you can determine the image size that I
see.

> VF = Viewing Factor = Final Image size diag. / View distance.
> (1=Normal VF, 53 deg AFOV, <1=WA VF, >1=tele VF)

For projection, from the location of the projector, from similar
triangles:
Image Size diag / Viewing distance =(appr) Film size diagonal / FL of
projector lens.

I was projecting stereo realist format and the image diagonal is
approximately 35mm, so significant "stretch" was occurring with the 125mm
lenses.

If you are standing by the projector, then you can consider the projector
lens FL to be the equivalent of the viewing lens FL in a viewer. A
typical realist format viewer has FL of 44mm. The projector with a 125mm
lens will create significant stretching, compared to the viewer. But this
comparison applies only for the projectionist or anyone standing by the
projector. Those sitting closer or further back see a different image in
terms of stretch.

George

I do not get this... I think if PF = 1 then you have ortho viewing, no
matter what the individual values of CPF and VF are...

If you take a picture with a wide angle lens and you view it close enough
(so PF = 1) you get the correct perspective. If you take a picture with a
telephoto lens and you view it from a distance, you see a smaller image,
but correct perspective.

Why do you say that for ortho-viewing both factors should be equal to one?
I think only the product matters. The individual factors only affect the
size of the final image, not the perspective. The pictures are *exactly*
the same (minus distortions caused by wide angle lenses).

George

> PF = CPF * VF
>
>
> CPF = Capture Perspective Factor = capture lens fl / capture media
> diag.
> (1= Normal CPF, <1 = Wide angle CPF, >1 = long CPF)
>
>
> VF = Viewing Factor = Final Image size diag. / View distance.
> (1=Normal VF, 53 deg AFOV, <1=WA VF, >1=tele VF)
>
>
>
> When PF = 1, you have Normal viewing Perspective Factor, however, a
> distinction should be made....
>
>
> True Ortho viewing only takes place when CPF and VF = 1. Other
> combinations which create PF = 1, are considered "corrected
> perspective", a slight distinction as the final views under these two
> scenarios are not EXACTLY the same.

Regarding 2162,

.4x x 80mm, or .4x 75mm, begets us a 32mm fl, or a 30mm MF lens,
respectively. I am not aware that either a 32mm or a 30mm lens are
avilable for use on any MF camera that I am aware of. I do not
consider the fish-eye lenses as being an option.

I am curious as to how the test was performed, with non existant
lenses ?


DON

Hi Don!

> .4x x 80mm, or .4x 75mm, begets us a 32mm fl, or a 30mm MF lens,
> respectively. I am not aware that either a 32mm or a 30mm lens are
> avilable for use on any MF camera that I am aware of.

Correct Don, in my case, I used a 35mm fl MF lens,
and viewed the images with 80mm viewer lenses. Check out the
specifications on the Schneider 35mm Digitars, or even the Rodenstock
Digitals....

> I do not consider the fish-eye lenses as being an option.
> No Don, these are normal lenses, not fish-eye, and they produce fabulous images! I suggest you try a pair!
>

> I am curious as to how the test was performed, with non existant lenses ?
> Don, please explain what you mean by non-existant lenses? Do you mean they do not exist in your lens arsenal? Or do you mean they are non-existant on planet earth? I am confused, please clarify, so I can better respond.
>

Hi Doc

> If you are standing by the projector, then you can consider the projector
> lens FL to be the equivalent of the viewing lens FL in a viewer.

I am interesting in understanding what you write
above...forgive my lack of stereo projection experience. Following
what you wrote.... when you stand at the projector, this is equivalent
to viewing 35mm film with 125mm fl lenses, right? If so, this would
produce 17 deg. AFOV., which is equal to what a View Master viewer
creates. Even standing at the projector, I can't fathom the AFOV being
this small, as I thought the beauty of projection was the very large
AFOV's it offers? What am I missing here?

> The projector with a 125mm
> lens will create significant stretching, compared to the viewer. But this
> comparison applies only for the projectionist or anyone standing by the
> projector. Those sitting closer or further back see a different image in
> terms of stretch.
>
> George
>
>
>

Regarding 2164,

I disagree with the contention that only, 1/3rd if our sense of depth
comes from deviation. I believe that almost all of our sense of depth
comes from the use of our visual deviation.

I believe that the majority of our visual information is concerned
with views that encompass things that are within, about 25+/- feet
from our eyes.

I believe that use of our hands would be severely handicapped, without
the visual, deviation information, provided by our eyes.

Try doing something with your fingers when only one eye is available.


I believe that Le Roy is correct in dismissing the only 1/3rd allegation.


DON

> I do not get this... I think if PF = 1 then you have ortho viewing, no
> matter what the individual values of CPF and VF are...
>

It was a small distinction between true ortho, and
corrected Z-axis perspective. The small difference is in the 2d
image..... once an image is captured, the relationship of the near and
far subjects is fixed by the fl of the taking lens. (think of the same
composure with a 50mm fl lens and a 200mm lens) Viewing distance (or
magnification) will never change that relationship. What is corrected
when PF=1, as you point out, is the Z axis in stereo, which now provides
the correct amounts of convergence. Although it's a small distinction,
I was just being prepared for any hardcore true ortho's out there.

Michael K. Davis wrote:
[snip]

>
> So here it is in total, just as she translated it:
>
> Eyepiece: Each eyepiece 2 slices 2 groups.
>
> She says that any Chinese person who can read Chinese would get exactly
> that out of it and nothing more, so we have to make of it what we can.
>
> Does that mean 2 elements in each of two groups? One element in each of
> two groups? About the only thing we can say for sure about this line of
> text (if not the actual viewer) is that each eyepiece has TWO GROUPS, and
> that automatically means it's NOT an achromatic doublet. Hmmmmm...
>
> When I asked her if she thinks it means a total of 4 slices, two slices in
> each of two groups, she said, "It doesn't say enough for me to answer your
> question. It just says 'two slices, two groups', but I'm sure there are
> at least two groups and at least two pieces." I didn't bother to explain
> how an optics group can have either one element or multiple elements, etc.
> She's just telling me what the Chinese characters say.
>
> About the only thing we can say for sure about this line of text (if not
> the actual viewer) is that each eyepiece has TWO GROUPS, and I think that
> automatically means it's not an achromatic doublet, because a double is
> always described as a single group, right?

First, as previously mentioned, this is all conjecture.

From what your co-worker translated, I would assume that "slices"
means elements. I would probably further assume that means two
elements (total) in two groups. I think assuming two elements per
group is stretching it a bit, especially since George has said that
the price will not go up.

Two elements in two groups could be an air spaced doublet. Such an
arrangement can be achromatic.

--
Brian Reynolds | "It's just like flying a spaceship.
reynolds@panix.com | You push some buttons and see
http://www.panix.com/~reynolds/ | what happens." -- Zapp Brannigan
NAR# 54438 |

Hi Don!

>
> I believe that use of our hands would be severely handicapped, without
> the visual, deviation information, provided by our eyes.
>

Deviation surely helps.....have you ever
seen a jeweler working on the mechanics of a tiny watch? With nothing
but one monocular in his eye? It's incredible how they can discern
depth planes which are often .x mm apart with only one eye.....

>
> I believe that Le Roy is correct in dismissing the only 1/3rd allegation.
>

Don, I know you used to do a lot of
research on human vision at the University level. Maybe you can
provide some resources that discusses this in more depth so we can learn
more about the topic. I do not have all my references handy, but I did
copy one page that might be of interest. Here it lists 13 depth cues
the brain uses to analyze depth. Of the 13 total, 11 of them are
perceived via monocular vision. The other two cues come with Binocular
vision, which are the obvious Disparity and Convergence. Let me know
what your resources offer, as you probably have more thorough resources
than most of us....thanks Don... Have a look....

*http://tinyurl.com/5tkld2

Bill


*

Hey Brian,

At 11:29 PM 7/30/2008, you wrote:

>First, as previously mentioned, this is all conjecture.

Right - we don't know that these specs accurately describe the
forthcoming viewer.

> From what your co-worker translated, I would assume that "slices"
>means elements. I would probably further assume that means two
>elements (total) in two groups. I think assuming two elements per
>group is stretching it a bit, especially since George has said that
>the price will not go up.

I hear you. Going by the translation, we can conjecture that each
eyepiece has two elements and we can conjecture that each eyepiece
has two groups. That's about all we can conclude.

>Two elements in two groups could be an air spaced doublet. Such an
>arrangement can be achromatic.

So, it's possible to have two groups and still have only one
achromatic doublet... I didn't know that.

Thanks,

Mike Davis

Regarding 2168:

Not a surprise, the focal length of the reference lens has not
been mentioned. The MF camera has not been described, either.

If the .4X lens is a 35mm lens, this would indicate that the
reference lens had a focal length of 87.5mm. (2.5 x 35 = 87.5mm).

I consider a 87.5mm fl to be an odd focal length for a taking
lens.

Apparently, the 2x lens had a focal length of about, 195.5mm,
(2 x 87.5mm =195mm). Another odd focal length.

I consider the Digitar lens to be too expensive, and present a
case of over-kill, (as regards to resolution), if used on the
available transparency films, none of which offer a high degree
of resolution that will show the potential of the high resolution
capable Digitar lens.

In my previous post, I mentioned that I was not aware of avail-
ability of either a 30mm or a 32mm fl MF lens. Was I in wrong ?

DON

--- In MF3D-group@yahoogroups.com, "Michael K. Davis"
wrote:

> The next two characters are the SAME as those to the left of the

colon:

>
> Eyepiece
>
> The next two characters mean: 2 slices
>
> (She emphasized that this character refers to a flat slice of

something or

> a flat piece of something - as you would say when refering to a

piece of

> paper - something planar - her words.)
>
> The last two characters mean: 2 groups
>
> So here it is in total, just as she translated it:
>
> Eyepiece: Each eyepiece 2 slices 2 groups.
>
> She says that any Chinese person who can read Chinese would get

exactly

> that out of it and nothing more, so we have to make of it what we

can.

>
> Does that mean 2 elements in each of two groups? One element in

each of

> two groups?

That's easy to decipher ! What they are saying is that you get two
SLICES of lenses with the viewer. If you want the WHOLE lenses,
you'll have to pay more !

Francois

--- In MF3D-group@yahoogroups.com, Bill G wrote:

>
> Hi Leroy
> >
> > I strongly disagree with the ³1/3 of our sense of depth comes

from

> > deviation,² at least if I understand what you are saying.
> >
> > ALL of our sense of STEREO depth comes from deviation.
> >
> The military has done some

extensive

> testing in this area, as well as lots of optical researchers....

it came

> as a surprise to me as well.... IIRC, one text I read stated

deviation

> representing as low as 25% of our total depth cues. As an

interesting

> experiment, cover one eye and look at an area that you have never

seen

> before, and see if you can place all the subjects in depth

order.... I

> did this several years ago, and remarkably, I could place the

depth of

> objects as well with one eye as I could two, except maybe when

they got

> really far, say 70ft+. So, I became a believer....

The problem with your example is you are not taking into account
that the subjects you are looking at are already familiar to you
even if you have not seen that scene before. So you can estimate
their distance by the fact that you recognize their nature and are
familiar with their size and the fact closer objects cover farther
ones.

Furthermore, you are looking at a THREE-DIMENSIONAL scene and the
slightest eye movement or body wavering can give you parallax
information.

It's quite a different story if you are looking at a TWO DIMENSIONAL
picture of a three dimensional scene where eye or body movement
cannot pick out parallax information since it is absent from the
picture.

Sure, you could estimate distances of some RECOGNIZABLE objects
based on their simple shapes and relationships, but not so if the
shapes are complex and intricate. Try to make out the distance of
individual branches in a 2D picture of a tree... or try to figure
out distances in a picture of subjects you are not familiar with or
in an abstract composition. That will prove impossible without
parallax.

Francois

>

Hi Don!

>
> Not a surprise, the focal length of the reference lens has not been mentioned.

Re-read my last post Don, Digitar 35mm fl.

> The MF camera has not been described, either.
>

Home brew stereo camera and cha cha. If required,
I will send you the referenced camera and referenced lenses for your
inspection..... please advise.....

> If the .4X lens is a 35mm lens, this would indicate that the
> reference lens had a focal length of 87.5mm. (2.5 x 35 = 87.5mm).
>

OK, I did not know we were knit picking
here. I remember countless posts in the past where you hammered people
on this list for providing too much accuracy in their numbers during
general exchanges..... and now, it seems you have jumped the fence,
turning general discussions into detailed minutia. But in all
fairness Don, lets be exact, here is my revised statement....


I have used taking lenses of a fl, .438 of the fl of the viewing lenses
and the Z axis appears completely normal. I assume this statement has
mores merit now??? Glad we got to the bottom of that ONE! Sheeesh!

> Apparently, the 2x lens had a focal length of about, 195.5mm,
> (2 x 87.5mm =195mm). Another odd focal length.
>

You sure make a lot of assumptions Don....
the viewing lenses were 44mm fl, and the taking lens was a 90mm fl,
another Digitar. Oooops, I am a few decimal places off again, damn
it, another revised statement.....


I have used taking lenses which are 2.04 times the viewing fl lenses
(44mm) and the Z axis appears to be completely normal. Now you are OK
with my statement?

> I consider the Digitar lens to be too expensive, and present a
> case of over-kill, (as regards to resolution), if used on the
> available transparency films, none of which offer a high degree
> of resolution that will show the potential of the high resolution
> capable Digitar lens.
>

I was not aware you used the Digitar lenses....
I am interested in your experience with them... were they no sharper
than Spud lenses when compared side by side? I have had excellent
results with them.... I remember after you viewed M7 lenses at a trade
show, you raved on this list how amazing sharp they were, remember?
Did you change your tune about high-end MF lenses? IMO, I would
categorize the digitars equal or a tad sharper, they are both superb.
So what gives Don? I am confused of your changing positions.... please
help....

> In my previous post, I mentioned that I was not aware of avail-
> ability of either a 30mm or a 32mm fl MF lens. Was I in wrong ?
>

I don't know Don, and I don't have time to go
research it for you. I did modify my statements so the are accurate
down to .0x factors. As I do agree with you, this discussion made no
sense till we tightened up these parameters. Thanks for catching these
silly errors on my behalf... ???@#$%?Q#$?#


Bill

Regarding depth cues in, 2173:

Is it possible for a Jeweler to use a pair of loupes to
focus on the interior of a watch, so as to view the in-
terior of the watch in 3D ? The interior of the watch
is, probably, less than an inch wide, and the Jeweler
probably has eyes that have an IPD of about 2 1/2 inches.

Please explain how a Jeweler could view the interior of a
watch, getting a magnified view of the interior in 3D ?


Lots of luck,

DON

Francois

>
> The problem with your example is you are not taking into account
> that the subjects you are looking at are already familiar to you
> even if you have not seen that scene before.

Ahhhh, I guess that is a problem? Or
is it? Everything I take stereo pictures of, I have pretty much seen
before? We can't change that, can we?

> So you can estimate their distance by the fact that you recognize their nature and are
> familiar with their size and the fact closer objects cover farther ones.
>

This is sometimes true, but often not
true.... for example, when in a forest, I have properly placed the depth
order of trees of all different sizes..... give it a try... is it easier
with two eyes? Of course, cause it adds information..... but i think I
am batting better than .900 with one eye, not so bad..... better than I
ever suspected.

> Furthermore, you are looking at a THREE-DIMENSIONAL scene and the
> slightest eye movement or body wavering can give you parallax
> information.
>

Agreed, but that was not the case, but
regardless, its still one eye. Why not try it first, then take a
position?

> It's quite a different story if you are looking at a TWO DIMENSIONAL
> picture of a three dimensional scene where eye or body movement
> cannot pick out parallax information since it is absent from the
> picture.
>

I have taken identical images with my
M7, no deviation at all and mounted them. When viewed, only about 10%
of people could pick up on the fact there was no deviation and even
then, they weren't sure what was different. I would probe them with
questions......does anything look unusual (after seeing many slides with
deviation) and almost everyone still says, no, it's sooo nice... etc.
That's been my experience... I would be interested in hearing your
experiences doing the same. Of course many of us are keen observers,
specially if you know the background information, your knowledge will
influence your thinking..

> Sure, you could estimate distances of some RECOGNIZABLE objects
> based on their simple shapes and relationships, but not so if the
> shapes are complex and intricate. Try to make out the distance of
> individual branches in a 2D picture of a tree... or try to figure
> out distances in a picture of subjects you are not familiar with or
> in an abstract composition. That will prove impossible without
> parallax.
>

Ahhhh, now you have isolated situations
where deviation can be very helpful. But who was ever arguing that
point? Certainly not me.... I only mentioned, its amazing how many
depth cues the brain can analyze from monocular vision, confirmed by
many studies.... then I did some testing on my own and found it to be
very true..... You seem to be suggesting I believe the added
deviation and convergence info is useless? Huh?

Hi Don!

> Regarding your response to post #2173: Please explain how a Jeweler could view the interior of a watch, getting a magnified view of the interior in 3D
> Lots of luck,
>

Who ever suggested the Jeweler could use
both eyes when viewing objects so close? Certainly not me.... I only
was mentioning when you put a 10x magnifier in one eye, how easy it is
to discern depth planes at .x mm distances apart. That was all I said
Don, I am not sure where your assertions come from..... maybe you dream
them up for ammunition? So far Don, all my responses to you are a
result you not comprehending my previous post, or nit picking something
for no apparent reason. I have hung in there with ya for awhile out
of courtesy, but I must admit, it's getting really tedious... not sure
of your motive..... but I probably won't be the last person you drive
back into lurker mode..... if that was your motive, congrats ....

Bill

Regarding 2181, my retort was aimed at the allegation that only
1/3rd of our sense of depth resulted from visual deviation. Look-
ing around, with a single eye, I found my sense of depth to be very
limitted, unless I moved my head. I assume that with the passing
of time, my one eyed depth perception would improve, but I am not
aware that the allegation allowed for learning. My conlusion was
that visual deviation was of significant help when doing my daily
chores, including my one fingered keyboard typing. I did not
understand how the mention of the Jeweler fit into the issue, as a,
visual deviation, was not an option when a single eye is being used.
In the same way, a visual de- viation is not an option when dist-
ances farther than about 100 yards are involved.

As regards to the suggestion that the theory that, 'there is com-
pression/ expansion on the Z axis is a non issue, the supporting
facts were very vague. The test was made with a normal fl viewing
lens, a 2X fl lens and a .4X of the normal fl lens. No numbers were
given. The total range was 5 to 1, the longer fl lens being 5 times
the length of the shortest fl lens. I found it difficult to believe
that there was not a visual problem when such a wide range of viewer
lens focal lengths was used. Dr T mentioned that he could see a,
compression/expansion problem when he compared what he saw when
viewing a slide with a 44mm fl lens as compared to what he saw when
he viewed a similar slide with a 35mm fl viewer lens.

As far as me being critical of someone using too much precision,
that has not been the case. I have been critical when false precis-
ion has been suggested, which usually involved the use of impossible
precision, such as when the on film deviation being claimed to be
measured to being 2.24mm. I am not aware that this degree of accu-
racy, (1/100th of a mm), is visually probable.


DON

Hi Don!

> Regarding 2181, my retort was aimed at the allegation that only
> 1/3rd of our sense of depth resulted from visual deviation. Look-
> ing around, with a single eye, I found my sense of depth to be very
> limitted, unless I moved my head.

Don, I was only offering information
provided by several optical research studies.... isn't that what the
forum is for? Since you studied these topics at the University level
many years ago, why not find us some hard data from your wealth of
resources? I thought you would provide more concrete evidence than
walking around the house with one eye closed? You are a man of facts,
studies, concrete evidence, exactness, right?

> I did not understand how the mention of the Jeweler fit into the issue, as a,
> visual deviation, was not an option when a single eye is being used.
>

For the 3rd time now..... I never suggested
binocular vision was an option.... what I was suggesting, which you are
still not grasping, is the tremendous depth the jeweler can sense with
just one eye.... I have done this myself, and it is amazing how one eye
and the brain can discern such tiny depth planes WITHOUT the use of
disparity. Now do you understand it?

>
> As regards to the suggestion that the theory that, 'there is com-
> pression/ expansion on the Z axis is a non issue, the supporting
> facts were very vague. The test was made with a normal fl viewing
> lens, a 2X fl lens and a .4X of the normal fl lens. No numbers were
> given.

In the future, I will provide a "white
paper" which is peered reviewed before I post it on the forum, is that
more to your liking? I certainly did not mind providing you the data
you suggested, but when I did, your next combative move was to nail down
.0x levels of factors I used in a general discussion. IMO Don, it
seems your motive is to be combative for no apparent reason, certainly
not to further the sharing of useful information. In that regard, all
you seem to offer is..... " I was not aware such alleged claim".....of
course, you never back anything up with good resources.

>
> As far as me being critical of someone using too much precision,
> that has not been the case.

It certainly was the case here Don,
please re-read my last post. You bickered over 2x vs. 2.03x. ???
Yep, of course, as with many of your assertions, they are based on poor
assumptions on your behalf...but instead of asking for information, you
simply assume, then become combative with your replies, as you have way
too much confidence in your assumptions.... your pattern has been quite
consistent.

> I have been critical when false precision has been suggested, which usually involved the use of impossible precision,

Yes, you are now supporting my claim! This
was my point, just like you raving over the M7 lenses on this forum,
then the digitar lenses which are equally sharp, you find them
overpriced and not necessary because todays poor color film can not
record their superior aerial resolution??? HUH??? Or where you just
in a combative mood for when you wrote that statement, it doesn't jive
with your previous statements Don? Of course, you conveniently
ignore these comments in your next posts.........



Anyway Don, I have tried my best to be fair
and respectful of your combative nature, but I can no long play ball.
In order to continue, I would need to hire an assistant dedicated to
addressing your posts, re-typing the same things over and over, having a
research team send you back-up data, proof of certain lenses and cameras
that exist..... as it seems if you don't own something or unaware of
it, than it must not exist on planet earth. Our personal experience
from testing, posting tons of data for the list to view, etc. is never
sufficient to meet your analytical thresholds....even though you offer
no conflicting test data on your end? And all this, for a hobby, huh ?


So I gave it my best shot Don, but it's just too
exhausting.... there is plenty of other people on this forum you have
good relations with, so you will have plenty of people to converse
with..... Happy shootin Don!


Bill

--- In MF3D-group@yahoogroups.com, Bill G wrote:

>
> Francois wrote:
> > The problem with your example is you are not taking into account
> > that the subjects you are looking at are already familiar to you
> > even if you have not seen that scene before.
> Ahhhh, I guess that is a

problem? Or

> is it? Everything I take stereo pictures of, I have pretty much

seen

> before? We can't change that, can we?

I was referring to the claim that you can tell the distances of
subjects without the aid of stereopsis. That is possible in general
if the scene is familiar to you as I stated.

> > So you can estimate their distance by the fact that you

recognize their nature and are

> > familiar with their size and the fact closer objects cover

farther ones.

> >
> This is sometimes true, but often

not

> true.... for example, when in a forest, I have properly placed the

depth

> order of trees of all different sizes..... give it a try...

Why would you presume I have not ? I have been observing those
effects ever since I started in stereo photography 28 years ago. In
your example you are using again a very familiar subject and again,
the subject you are looking at is a real 3D scene not a 2D picture
of it... In such a case, even if you are not moving, subtle eye and
head movements can help discern parallax.


is it easier

> with two eyes? Of course, cause it adds information..... but i

think I

> am batting better than .900 with one eye, not so bad..... better

than I

> ever suspected.

As I stated in my original post, I am talking about INTRICATE
details such as the tree BRANCHES... such as if one tries to count
the tree branches with one eye without moving one's head or eye...
or if one tries to do the same on a 2D picture of tree branches...

> > Furthermore, you are looking at a THREE-DIMENSIONAL scene and

the

> > slightest eye movement or body wavering can give you parallax
> > information.
> >
> Agreed, but that was not the case,

but

> regardless, its still one eye. Why not try it first, then take a
> position?

I am talking from repeated experiences on my own. I amazed you keep
taking the position that I never tried any of this myself over the
last 28 years ! I am merely pointing out your one eye is looking at
a three-dimensional scene not a 2D picture of it.

> > It's quite a different story if you are looking at a TWO

DIMENSIONAL

> > picture of a three dimensional scene where eye or body movement
> > cannot pick out parallax information since it is absent from the
> > picture.
> >
> I have taken identical images

with my

> M7, no deviation at all and mounted them. When viewed, only

about 10%

> of people could pick up on the fact there was no deviation and

even

> then, they weren't sure what was different. I would probe them

with

> questions......does anything look unusual (after seeing many

slides with

> deviation) and almost everyone still says, no, it's sooo nice...

etc.

> That's been my experience... I would be interested in hearing

your

> experiences doing the same.

My experience of doing the same yielded somewhat different results.
I guess it depends on the type of picture that is shown. In fact,
this reminds me of a View-Master test reel where half of the picture
is in 3D and the other half is in 2D. The difference is dramatic.
Of course if the photographs taken show subject matter where there
is no close range subject, the differences can be subtle and I agree
some people might not notice the difference if the pictures are
shown separately, but the difference would become clear if the two
pictures were shown side by side. But with high impact 3D and
intricate compositions, the differences are dramatic.

I tested this by telling people (while they were looking through the
oculars of a stereo viewer) to close one eye for a few seconds and
then open it. The scene showed a cherry blossom in bloom. With one
eye, all they saw was an incomprehensible mess, but when they opened
the second eye, everything popped out in glorious 3D and they
went "WOWWWWWWWW... Amazing !!!" ;-)

> > Sure, you could estimate distances of some RECOGNIZABLE objects
> > based on their simple shapes and relationships, but not so if

the

> > shapes are complex and intricate. Try to make out the distance

of

> > individual branches in a 2D picture of a tree... or try to

figure

> > out distances in a picture of subjects you are not familiar with

or

> > in an abstract composition. That will prove impossible without
> > parallax.
> >
> Ahhhh, now you have isolated

situations

> where deviation can be very helpful. But who was ever arguing

that

> point? Certainly not me.... I only mentioned, its amazing how

many

> depth cues the brain can analyze from monocular vision, confirmed

by

> many studies.... then I did some testing on my own and found it to

be

> very true..... You seem to be suggesting I believe the added
> deviation and convergence info is useless? Huh?

I am simply trying to clarify that viewing a 3D scene with one eye
is something very different from viewing a 2D picture with two eyes.

>
> I was referring to the claim that you can tell the distances of
> subjects without the aid of stereopsis. That is possible in general
> if the scene is familiar to you as I stated.
>

The scene does NOT have to be familiar to
you, often there is sufficient monocular depth cues whereas you can
decipher depth without deviation / convergence. Is it 100%, of course
not, no one ever claimed it was. But it's shocking how good our
monocular depth perception is...

>
>
> As I stated in my original post, I am talking about INTRICATE
> details such as the tree BRANCHES... such as if one tries to count
> the tree branches with one eye without moving one's head or eye...
> or if one tries to do the same on a 2D picture of tree branches...
>

which I agreed, right? adding convergence
and deviations certainly can help in some situations, we all agree on
that, right?

>
>
> I am talking from repeated experiences on my own. I amazed you keep
> taking the position that I never tried any of this myself over the
> last 28 years ! I am merely pointing out your one eye is looking at
> a three-dimensional scene not a 2D picture of it.
>

Look at a 2d picture, see how well you
place depth objects in the scene.... its still very impressive....

>
> I tested this by telling people (while they were looking through the
> oculars of a stereo viewer) to close one eye for a few seconds and
> then open it. The scene showed a cherry blossom in bloom. With one
> eye, all they saw was an incomprehensible mess, but when they opened
> the second eye, everything popped out in glorious 3D and they
> went "WOWWWWWWWW... Amazing !!!" ;-)
>

I can assure you, if this same scene
was two, 2-D images, you would get a "similar" reaction. Most of this
is accounted for in binocular summation effect...added perceived light
of about 1.4x, significant added resolution with two eyes (brain has
more data to process) and the natural component of having two eyes
open. So while the deviation component helps, it does not account for
100% of the added WOW...


Case in point..... when I view through
my 102mm APO refracting telescope with the use of a Binoviewer.....
which converts the single image formed by the objective lens into a dual
carbon copy images...... which you must use two eyepieces in the
binoviewer....it comes with IPD adjust and ind. eye focus, of course....


I do the exact same experiment you describe.... I tell people look
through one eye..... and its still impressive as a good APO scope
produces some of the highest resolutions imagery possible.... Then I
say, OK, now open the other eye....and whamo, WOWWWWWW.... get my
drift, there is only one flat image as the source, and its overwhelming
the power of binocular summation, even when looking at a 2d image. Of
course, these are ultra high res real world scenes which provides even
more rez than film could ever hold.


I have also used this same arrangement viewing an 8x10 piece of color
film on a high powered light box.... which simulates a dual eye view of
a flat 2d single image, at 82 deg AFOV, with tremendous resolution as
its 8x10 film. I have had people tell me they think this view is
better than my MF home-brew viewer in STEREO!..... yep... and it's in
2d (but dual eye with amazing AFOV) and I can understand this, because,
the 8x10 film overwhelms your senses with resolution, which is quite
captivating. So my point is, there is a lot of variables at play here,
not just the depth component. Of course, I don't plan to shoot dual
2d, because I want that added element, but I have considered making a 2d
viewer as it can deliver visual components not possible with current 3d
viewers, which uses loupe to film path..

>
> I am simply trying to clarify that viewing a 3D scene with one eye
> is something very different from viewing a 2D picture with two eyes.
>

I concur on this point.... viewing a real
world scene with one eye will often give our brains more data vs.
looking at a 2d print. But even in the telescope example above, when
I view single piece of 8x10 film, the view is spectacular, and depth is
very apparent.... Before seeing this, I would have resisted this too,
because, I put such emphasis on deviation when I started stereo
photography.... live n learn...


Bill

>
>
>
>

Recently I suggested that I considered the Digitar lenses to be expensive.

In Seattle, a single 35mm fl Digitar lens costs $3606.95 up to
$3793.50, depending on the shutter combination.

I read that a 44mm fl viewer lens had been used to view MF stereo
slides. Sounds like an interesting viewer lens, if it does exist.

I was asked, were the Digitar lenses no sharper than the Sputnik
lenses, which came as a surprise, considering that I was not aware
that Sputnik lenses were considered to be sharp.


DON

In 2143, the term, "projection stretch", was used.

I have been under the impression that, in stereo, "stretch"
is a product that is built into the stereo slide.

I am not aware that the distance to the projection screen
will alter the degree of stretch that has been built into
the stereo slide image.

In my opinion, a hyper stereo slide image will continue to
present a toy-like image, whether one is close to the pro-
jection screen, or is 2 or 3 times as far from the screen.


DON

--- In MF3D-group@yahoogroups.com, Bill G wrote:

>
>

> > I tested this by telling people (while they were looking through

the

> > oculars of a stereo viewer) to close one eye for a few seconds

and

> > then open it. The scene showed a cherry blossom in bloom. With

one

> > eye, all they saw was an incomprehensible mess, but when they

opened

> > the second eye, everything popped out in glorious 3D and they
> > went "WOWWWWWWWW... Amazing !!!" ;-)
> >
> I can assure you, if this same

scene

> was two, 2-D images, you would get a "similar" reaction.

I disagree here also as I did test this and did NOT get the same
reaction. In fact, it is this test which motivated me to start out
in 3D in the first place. I did a series of tests with a slide bar
where I would shoot three pictures. Two with zero deviation and the
third with a normal base. When viewing the two identical slides in
a stereo viewer, it looked flat and blah. But when I viewed the
stereo version, it popped out in 3D. I was amazed that I could see
each blade of grass and each tree branch distinctly. I showed the
pictures to several people and all concurred. And that is why I
decided to invest in a camera with two lenses. Why else would I ?

Since then, when I show stereo slides, some people do ask me if they
could get a similar effect by putting two of the same slides in the
viewer. I then show them my test slides without deviation and they
immediately remark it looks like looking at a 2D picture on a wall.

> but I have considered making a 2d
> viewer as it can deliver visual components not possible with

current 3d

> viewers, which uses loupe to film path..

This concept was applied in several bi-lens 35mm slide viewers of
the fifties. Viewing with two eyes a monoscopic image still results
in a flat image being viewed. Again, it only makes a difference in
respect to eye convergence and gives one the impression of viewing a
flat movie screen some distance away.

Francois

> I disagree here also as I did test this and did NOT get the same reaction.

Due to the number of variables at play here,
such as, light levels, quality of image, quality of film, quality of
optics, AFOV, etc., its hard to compare the results of two tests which
used completely different set of variables....

> And that is why I decided to invest in a camera with two lenses. Why else would I ?
>

hmmmm, because you prefer to add deviation to your
photography? I know that is why I added the second lens..... it's more
information for the brain to work with... more potential for WOW?

> This concept was applied in several bi-lens 35mm slide viewers of
> the fifties. Viewing with two eyes a monoscopic image still results
> in a flat image being viewed. Again, it only makes a difference in
> respect to eye convergence and gives one the impression of viewing a
> flat movie screen some distance away.
>

I can understand a test done in the 50's, with
the optics and film available at the time, would result in this
finding. However, when you change many of the viewing variables, (not
just eliminating deviation and keeping all the other variables the same)
the over-all experience can change radically, at least using modern
optics available today. One of the points i was making was.....,
when viewing a single image with two eyes, there is more optical
potential than what's available when viewing stereo (deviated) images,
with two eyes. At least considering what has been available to date in
terms of stereo viewers. (or anything that will ever be available in
our lifetime)



A perfect example is..... viewing a scene 25
ft away with a mediocre pair of binoculars, 10x30 with standard 45 deg
AFOV, the scene still provides tremendous depth via deviation, just like
a stereo viewer. I would say this would be on par with a good 35mm
stereo viewer with good film.



Next, you view that same scene through a 140mm
APO telescope (obviously NO deviation) with a bino viewer using two 80 -
100 deg AFOV EP's.... out of 100 people, I would bet 99 of them would
MUCH MUCH prefer the non deviated image, as it brings so much more to
the table in terms of visual experience.... resolution, detail,
contrast, image brightness, AFOV, etc. When your retina is
overwhelmed with 10x the detail, approx. 1,000x increase in light
intensity, 5x greater retina fill (ridding tunnel vision) it's amazing
how many depth cues begin to surface. You swear it's a 3d image.
Out of the 100 test subjects I mentioned above, I included the "1" out
of 100, just in case you were involved in the test :-)


Anyway, IMO, we have done different tests, with different
equipment, using different visual variables, hence why we probably have
completely different findings.....

Donald Lopp wrote:

>I have been under the impression that, in

stereo, "stretch"

>is a product that is built into the stereo

slide.

Not so Don. It is a result of viewing with an
overall magnification less than one. The angle
of view to the image (on screen or wherever) is
less than it was in real life.

>In my opinion, a hyper stereo slide image will

continue to

>present a toy-like image, whether one is close

to the

>projection screen, or is 2 or 3 times as far

from the screen.

That is not "stretch", it is "lilliputism".
(See Ferwerda 8.2 & 24.7)


Chuck Holzner

> I have been under the impression that, in stereo, "stretch"
> is a product that is built into the stereo slide.
>
> In my opinion, a hyper stereo slide image will continue to
> present a toy-like image, whether one is close to the pro-
> jection screen, or is 2 or 3 times as far from the screen.

There are two issues that are sometimes confused.

1. If the stereo base is increased, the result is a hyperstereo. The
impression the viewer gets is that of a "toy-like" image. This affects
all three dimensions of the object.

2. If the viewing distance is larger than the recording distance, then the
image appears "stretched" in the 3rd dimension. This affects only one
dimension. The easiest way to experience this stretch is to look at a
lenticular image and gradually pull it away. You should notice this
"stretching" in depth.

The effect is rather subtle and it is not exactly proportional (i.e. if
you double the viewing distance you are not going to experience a doubling
of the stretch in depth) but it is unquestionably there.

George

> > question. It just says 'two slices, two

groups', but I'm sure there are

> > at least two groups and at least two pieces."

I didn't bother to explain

> > how an optics group can have either one

element or multiple elements, etc.

On the 3D-World site, they say the camera lenses
have 7 elements in 6 groups. No doubt that is
not 42 pieces of glass but only 7, two of which
are cemented together in a group. All the other
"groups" have only one element each.

2 elements in 2 groups would mean 2 "groups" of 1
element each. No?

Of course they can change it anytime they want.
%^)

Chuck Holzner

Bill wrote:

> A perfect example is..... viewing a

scene 25

> ft away with a mediocre pair of binoculars, 10x30 with standard 45

deg

> AFOV, the scene still provides tremendous depth via deviation,

just like

> a stereo viewer. I would say this would be on par with a good

35mm

> stereo viewer with good film.
>
>
>
> Next, you view that same scene through a

140mm

> APO telescope (obviously NO deviation) with a bino viewer using

two 80 -

> 100 deg AFOV EP's.... out of 100 people, I would bet 99 of them

would

> MUCH MUCH prefer the non deviated image, as it brings so much more

to

> the table in terms of visual experience.... resolution, detail,
> contrast, image brightness, AFOV, etc. When your retina is
> overwhelmed with 10x the detail, approx. 1,000x increase in light
> intensity, 5x greater retina fill (ridding tunnel vision) it's

amazing

> how many depth cues begin to surface. You swear it's a 3d

image.

> Out of the 100 test subjects I mentioned above, I included

the "1" out

> of 100, just in case you were involved in the test :-)

I guess you could make the same argument by saying that looking at a
sharp print is better than looking at a blurry one... except my
pictures were sharp ! ;-) Besides you're comparing poor 3D with
great 2D. My tests used the exact same equipment to compare zero
deviation with normal deviation.

Francois

Regarding 2191.

2191 alleged that viewing a scene 25 feet away with a pair of
binoculars 10 x 30 with a standard 45 degree AFOV, the scene
still provides tremendous depth via deviation, just like a stereo viewer.

An amazing proposition.

I am not aware that there are any 10X x 30mm binoculars, available,
that offer a 45 degree FOV, (field of view).

Most binoculars offer LESS than a 6 degree FOV.

Most Realist format stereo cameras offer, about, a 30 degree FOV.

I also read:

Next you view the same scene through a 140mm APO telescope, with a
bino viewer using 2, 80-100 degree AFOV EP's.

I don't know what was meant by the phrase- a 140mm APO telescope ?

Also, I do not understand what was meant by the phrase- bino viewer
using 2, 80-100 degree AFOV EP' ?

I am not aware of any, consumer level stereo viewers that offer a 80
to 100 degree FOV ?

I don't believe the, allegation, that suggested that a pair of 10X
binoculars will increase the light intensity by 1000X, has any
merit. If true, how would binoculars be of any use in areas that
have snow ?


DON

Don wrote:

>
> Regarding 2191.

I wish you would reply to the messages you are commenting on. Those
numbers are only useful to people who read this mailing list on the
yahoogroups website.

> 2191 alleged that viewing a scene 25 feet away with a pair of
> binoculars 10 x 30 with a standard 45 degree AFOV, the scene
> still provides tremendous depth via deviation, just like a stereo viewer.
>
> An amazing proposition.
>
> I am not aware that there are any 10X x 30mm binoculars, available,
> that offer a 45 degree FOV, (field of view).
>
> Most binoculars offer LESS than a 6 degree FOV.

Whoever you are responding to said AFOV, not FOV (aka True Field Of
View, TFOV).

Apparent Field Of View (AFOV) is the field of view you perceive when
looking through an optical instrument. This is determined by the
optical and mechanical design of the eyepiece used. Eyepieces of the
same focal length can have widely different AFOVs. For example, I
have a Televue 25mm Plossl with an AFOV of 50 degrees. Televue also
sells a 24mm Panoptic with an AFOV of 68 degrees, and a 26mm Nagler 5
with an AFOV of 82 degrees. The three different optical designs
(Plossl, Panoptic, Nagler 5) are what primarily determine the AFOV,
but mechanical constraints also effect AFOV. The Televue 40mm Plossl
only has a 43 degree AFOV because the 1-1/4 inch eyepiece barrel
limits the view. The Nagler 5 is a 2 inch eyepiece.

AFOV is related to the TFOV by the magnification of the complete
optical system. In the example quoted above, a pair of 10x30
binoculars with an AFOV of 45 degrees would have a TFOV of 4.5 degrees
(45/10).

> I also read:
>
> Next you view the same scene through a 140mm APO telescope, with a
> bino viewer using 2, 80-100 degree AFOV EP's.
>
> I don't know what was meant by the phrase- a 140mm APO telescope ?

Astronomical telescopes are specified by their physical aperture and
focal ratio. A 140mm APO is an apochromatic refractor with a
(approx.) 5.5 inch diameter main objective.

> Also, I do not understand what was meant by the phrase- bino viewer
> using 2, 80-100 degree AFOV EP' ?

A binoviewer is a telescope attachment that allows you to view through
two eyepieces with matching focal lengths. Although the image is not
in stereo, observing with two eyes provides a better viewing
experience.

If you want to learn more I'd highly recommend reading through the
Televue <http://televue.com/> web pages. Besides show various
examples of these products, their website has very useful information
defining all the terms used.

--
Brian Reynolds | "It's just like flying a spaceship.
reynolds@panix.com | You push some buttons and see
http://www.panix.com/~reynolds/ | what happens." -- Zapp Brannigan
NAR# 54438 |

Brian Reynolds wrote:

>> Regarding 2191.
>>
> I wish you would reply to the messages you are commenting on. Those
> numbers are only useful to people who read this mailing list on the
> yahoogroups website.
>

Thank you Brian for picking up the
baton, I raised the white flag over a week ago..... as a result, I was
pursued off-list. You offered a very clear and concise response
below, although from past experience, I doubt it will accomplish its
task. :-(

I wish you the best of luck :-) and thanks again...

Bill

>
>> 2191 alleged that viewing a scene 25 feet away with a pair of
>> binoculars 10 x 30 with a standard 45 degree AFOV, the scene
>> still provides tremendous depth via deviation, just like a stereo viewer.
>>
>> An amazing proposition.
>>
>> I am not aware that there are any 10X x 30mm binoculars, available,
>> that offer a 45 degree FOV, (field of view).
>>
>> Most binoculars offer LESS than a 6 degree FOV.
>>
>
> Whoever you are responding to said AFOV, not FOV (aka True Field Of
> View, TFOV).
>
> Apparent Field Of View (AFOV) is the field of view you perceive when
> looking through an optical instrument. This is determined by the
> optical and mechanical design of the eyepiece used. Eyepieces of the
> same focal length can have widely different AFOVs. For example, I
> have a Televue 25mm Plossl with an AFOV of 50 degrees. Televue also
> sells a 24mm Panoptic with an AFOV of 68 degrees, and a 26mm Nagler 5
> with an AFOV of 82 degrees. The three different optical designs
> (Plossl, Panoptic, Nagler 5) are what primarily determine the AFOV,
> but mechanical constraints also effect AFOV. The Televue 40mm Plossl
> only has a 43 degree AFOV because the 1-1/4 inch eyepiece barrel
> limits the view. The Nagler 5 is a 2 inch eyepiece.
>
> AFOV is related to the TFOV by the magnification of the complete
> optical system. In the example quoted above, a pair of 10x30
> binoculars with an AFOV of 45 degrees would have a TFOV of 4.5 degrees
> (45/10).
>
>
>> I also read:
>>
>> Next you view the same scene through a 140mm APO telescope, with a
>> bino viewer using 2, 80-100 degree AFOV EP's.
>>
>> I don't know what was meant by the phrase- a 140mm APO telescope ?
>>
>
> Astronomical telescopes are specified by their physical aperture and
> focal ratio. A 140mm APO is an apochromatic refractor with a
> (approx.) 5.5 inch diameter main objective.
>
>
>> Also, I do not understand what was meant by the phrase- bino viewer
>> using 2, 80-100 degree AFOV EP' ?
>>
>
> A binoviewer is a telescope attachment that allows you to view through
> two eyepieces with matching focal lengths. Although the image is not
> in stereo, observing with two eyes provides a better viewing
> experience.
>
> If you want to learn more I'd highly recommend reading through the
> Televue <http://televue.com/> web pages. Besides show various
> examples of these products, their website has very useful information
> defining all the terms used.
>
>

> Regarding 2191., (2D vs 3D)

I am still puzzled by the test that, allegedly, compared a
view seen through a 10X bionocular which provides a, (2 foot
diameter), circular FOV at a distance of 25 feet. How this
small circular FOV can be compared with the approximate 6 foot
x 6 foot FOV offered by a Realist format stereo camera, at the
same 25 feet,causes me to wonder what information was gained
by alleged test.

Also, I have waited in vain for an explanation, concerning the
allegation that a 10X binocular will increase the light intensity
to the eye, by a factor of 1000.


DON

> Regarding 2191., (2D vs 3D)

I am still puzzled by the test that, allegedly, compared a
view seen through a 10X bionocular which provides a, (2 foot
diameter), circular FOV at a distance of 25 feet. How this
small circular FOV can be compared with the approximate 12 foot
x 12 foot FOV offered by a Realist format stereo camera, at the
same 25 feet,causes me to wonder what information was gained
by alleged test.

Also, I have waited in vain for an explanation, concerning the
allegation that a 10X binocular will increase the light intensity
to the eye, by a factor of 1000.


DON

This morning I read #2201 which suggested that I should have
given more information in my replies because those numbers,
such as, (# 2191) are only usefull to people who read this
mailing list on the Yahoo groups website.

A question, where else can anyone read my e-mail, (# 2198),
which contained questions, concerning, (# 2191) ?


DON

Personally, I read my messages in my Yahoo account to which they are instantly forwarded. Since I subscribed to a number of Groups, I can read all post and responses without jumping from one group to another, yet without the respective ##. Yours, Andreas --- On Fri, 8/8/08, dlopp2000 wrote: From: dlopp2000 Subject: [MF3D-group] Re: 2D vs 3D To: MF3D-group@yahoogroups.com Date: Friday, August 8, 2008, 12:16 PM This morning I read #2201 which suggested that I should have given more information in my replies because those numbers, such as, (# 2191) are only usefull to people who read this mailing list on the Yahoo groups website. A question, where else can anyone read my e-mail, (# 2198), which contained questions, concerning, (# 2191) ? DON

Don wrote:

>
> This morning I read #2201 which suggested that I should have
> given more information in my replies because those numbers,
> such as, (# 2191) are only usefull to people who read this
> mailing list on the Yahoo groups website.
>
> A question, where else can anyone read my e-mail, (# 2198),
> which contained questions, concerning, (# 2191) ?

I read my email with an email reader. Normally I use mutt on the
shell account provided by my ISP, although I have used Thunderbird
when I wanted to test access to the IMAP server running in my office.

--
Brian Reynolds | "It's just like flying a spaceship.
reynolds@panix.com | You push some buttons and see
http://www.panix.com/~reynolds/ | what happens." -- Zapp Brannigan
NAR# 54438 |

"dlopp2000" wrote:

>
> This morning I read #2201 which suggested that I should have
> given more information in my replies because those numbers,
> such as, (# 2191) are only usefull to people who read this
> mailing list on the Yahoo groups website.
>
> A question, where else can anyone read my e-mail, (# 2198),
> which contained questions, concerning, (# 2191) ?

Don, members of this and other yahoo groups can elect to read
messages on the group site where the numbers you cite are found. But
many of us prefer to receive individual email delivery to our
personal email accounts, and the message numbers are not included.
Also, folks who elect to receive daily digests by email rather than
individual messages will have a whole different numbering system of
digests, and these numbers will mean nothing to folks who receive
individual messages or who read messages on the website. Message
delivery settings can be easily adjusted, and individual groups
accessed via ones "mygroups" page,
http://groups.yahoo.com/mygroups
for those who do have and use a Yahoo ID/membership (rather than
having strictly an email subscription with no web access at all.)

So, quoting of (usually a small amount of) pertinent material is
helpful when you are replying to a previous message or messages. Hope
this helps. -Linda