Subject: The quest for the Holy Grail of MF optics....
Date: 2010-08-26 21:57:38
From: Bill G

> I had a chance to play with the De Wijs 50mm double achromats combi viewer lens barrels.
> The MF image area was just inside the edges, and when shifting the lens across, pin
> cushioning was pretty minimal, judging by the mount edges. The contrast seemed nicer than
> the 3D World viewer.
>
> Large, double achromats may be the way to go in the ongoing search....

Lattie, I admire your quest for the holy grail of MF viewer lenses.
I also have the Combi viewer and the lenses you mention, as you know, they are not
designed for MF images. But they do make "good" but not great 35mm viewer lenses.

Many of us have been on this search...some of us have gone over
cliff on this subject and designed / built such optics. In short, nothing really good is
available off-the-shelf. The reason is, every optic is designed to serve one set of
parameters. Using a lens designed for one set of parameters in a different application
will produce very compromised performance. Optics are very limiting in this manner...its
the nature of optics. Change one parameter, and the entire design changes. Same true
with camera lenses.

The general parameters for viewing optics are, the FOV of the optic must see
(film size), the fl of the lens, and the Eye Relief at the exit pupil location. The
performance characteristics of the optic is measured in MTF (the amount of film contrast
transferred to the eye throughout the image radius), image distortion, and a few different
sets of aberrations. Unfortunately, film died an untimely death, as its possible many of
the loupe manufacturers would have made better loupes to serve our purpose in MF...but
none did, I own them all. Had digital not taken over film, our prayers would have been
answered.

Each general, within each parameter is a zone of performance we desire...
the most critical parameter, (or the one that adds the most complexity to the lens design
for stereo viewing) is the lens fl. The fl, brings about the WOW factor we seek. In
more practical terms, the fl determines the HFOV (Horiz. Field Of View) we see when
looking at the film through the optic. A wide HFOV is very desirable, as you referred to
previously as the IMAX experience... you used a good analogy, so I will run with your
lingo to put viewing optics in perspective for you...

Imax theaters vary in size, but on avg., they will deliver about a 85 - 90 deg Horiz Field
of View (HFOV) at the center row. Our unaided vision sees about 120 deg total HFOV with
no head movement, but only about 90 deg in each eye, there is some non-common areas in our
temporal periphery. This large HFOV is what makes you feel so immersed in a IMAX
theater. A regular cinema (non IMAX) will have about a 55 deg HFOV in the center row,
quite a bit less. So how does this compare with optical stereo viewers?

38 deg HFOV = The 3dWorld MF viewers (75mm fl, 52mm wide film)

38 deg HFOV = The Combi viewer with 45mm fl lenses with 31mm wide film)

30 - 34 deg HFOV, most of the 1950's film viewers

15 - 20 deg HFOV for View Masters (different versions were tried)

So to go to the next step in MF viewing, you need better performing optics. However,
small gains in optical performance come at a very high price in glass size, weight, barrel
size and cost. To re produce the basic cinema experience, ~ 50 - 55 deg HFOV, requires a
5 - 6 element design at approx. 50 mm fl. The lens weighs about 2 lbs each, and is
about the size of your clenched fist. Of course, the size of the glass is also needed to
control distortion and produce sufficient Eye Relief (ER) for Eye Glass wearers. Cost to
make these in low volume say under 100 is about $1k each with machined barrels. This is
Asian manufacturing....in the USA, about 3x this cost. Then there is shared design and
prototype amortization. Of course a viewer would have to be designed around the lenses.
I have several of these lenses prototyped and use them for my home viewing, and yes,
they are a quite a treat. However, I accepted it is not commercially feasible to
manufacture them into a viewer, as the viewer would be very costly, in the $3 - $4k range.
Again, low volume kills everything. You can look at one of these lens designs here....

http://www.pbase.com/bglick/image/100722550

To reproduce the IMAX experience with MF film, would require a 10 - 12 element design,
preferably in a compound optic, or sometimes called a relay optic. This lens in low
volume would be in the $2500 per eye price range including the complicated barrels. As
you can see, high end optics can be very costly. Prototype and design fees can be in the
$30k - $200k range per lens based on the complexity. Here is a look at one of my early
attempts at this, but at only 60 deg... we later perfected this design to 90 degrees, but
with less ER..

http://www.pbase.com/bglick/image/100722439

Anyway, I hope this gives you a little better idea of the process and the complexity to
take MF viewing to the next level...vs. a basic doublet. It's too bad IMO, the 3dWorld
viewer did not provide enough ER in their doublet, as the ER is so short, probably 14mm,
the design rays can not land on the cornea (eye lens) for eye glass users, as his cornea
is too far from the glass. But the doublet I designed has more ER, about 20mm, only 5mm
less fl at 70mm, but is double the diameter and 4x the thickness. And just one of them
in low volume would cost more than the entire 3d world lighted viewer at $99. For non
eye glass wearers, the viewer is a bargain beyond belief. I think the Combi viewers are
about $750 now? + $250+ for light kit?

Anyway, I hope this gives you an idea of whats involved to try to improve upon the
existing products that are on the market today.... kinda sad, huh :-(

There actually is one bright spot, and that is 35mm viewing optics...they become MUCH
smaller and lower cost due to the smaller film size. So you can get the cinema (not
IMAX) experience for very low costs... but still a 5 element design. When I ask people if
they prefer my 35mm views using 50 deg HFOV optics (35mm fl), vs. my MF with the 3d World
viewer, they all prefer the 35mm views... HFOV seems to win every time, all else being
equal...

But once they view my MF images with the 50mm fl optics, (same HFOV as the 35mm optic
above) the MF trumps it every time.... less enlargement factor = better image quality.

Bill

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-08-27 06:46:34
From: lattie_smart

Zowie - talk about definitive! ;-O

Now I can sleep better knowing someone has been on the case! ;-)

I guess we omitted the LEEP optics, which sacrificed sharpness and aberration for HFOV?

Any opinion on the Pentax 5.5x? (Lot'sa eye relief traded for distortion?)

Some have made old, multi-element camera lens into serviceable 35mm loupes - but none would be wide enough for MF?

I keep imagining that in the future, there will be some kind of novel, electromagnetic light-wave bending devices that will replace glass altogether. But by then, they'll probably already come up with Star Trek style Holodecks, which will render mere "picture viewing" pedestrian.

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-08-27 06:47:50
From: lattie_smart

BTW, I have little problem using my 3D World with my glasses - maybe having to press my face into in a little.

The Saturn lens is wider - true - but not as ergonomic and well-lit!

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-08-27 08:58:56
From: Bill G

Hi Lattie

>
> I guess we omitted the LEEP optics, which sacrificed sharpness and aberration for HFOV?

The LEEP optic attempted, IIRC 90 deg HFOV... from the designs I saw,
it sacrificed just about everything, distortion was impossible to manage, aberrations
could not be controlled with so few elements, ER was not possible, etc. LEEP was a
pioneer...he was trying to develop an optic that was highly complex, during an era when
optical design software was non existent. It was the mid 90's when optical design
software started really benefiting the field. LEEP saw the Holy Grail long before any of
us...KUDOS to him for trying... (btw, LEEP was the name of the taking / viewing system,
not the person)

>
> Any opinion on the Pentax 5.5x? (Lot'sa eye relief traded for distortion?)

The Pentax loupe is designed for 35mm film, not MF. Viewing
outside a 12mm image radius, distortion is un controllable. It is a good loupe for 35mm
film... They were never designed to view a MF image circle. The best off-the-shelf
optics, that have benefited from modern design and glass improvements, ...

for MF is the Schneider 3x loupe (36 deg HFOV for 52mm wide film), but capable of
viewing a slightly larger film area than the 52mm width the 3d world mounts offer.
Excellent contrast over the entire image radius... good (not great ER, maybe 18mm)

http://www.bhphotovideo.com/c/product/214582-REG/Schneider_08_034551.html#features

And for 35mm, the Schneider asphericals are very good.... (best 35mm loupe available
off-the-shelf) Very reasonably priced... its a later design, so it has benefitted from
the use of an aspherical element vs. the earlier all spherical designs.

http://www.bhphotovideo.com/c/product/214580-REG/Schneider_08_034560.html#features

> Some have made old, multi-element camera lens into serviceable 35mm loupes - but none
> would be wide enough for MF?

The requirements for a camera lens, and a loupe are miles apart. As
others have had the same quest for the HOLY GRAIL of MF viewing optics, some have removed
1960's vintage camera lenses and used them as loupes. I can not comment on them, as I
have never seen them, but I would be shocked if a lens designed in the 60's for small
video format would be considered a high quality loupe for MF film. I think the appeal
was, it had a wide HFOV, which gave everyone the WOW factor they were looking for...

>
> I keep imagining that in the future, there will be some kind of novel, electromagnetic
> light-wave bending devices that will replace glass altogether.

They have..... 3d electronic displays. HFOV can be controlled by
eye-to-screen distance. Now the only optics required are "reading glasses" for those who
need accommodation assistance to view close objects. IMO, this is the future. Once 4MP
3d displays work themselves up in quality, and down in price, I think the viewing problem
will be history. (2MP 3d displays are in the marketplace now)

The technology already exist today for a small electronic viewer delivering
almost 2MP per eye, it would be smaller than a Red Button viewer.... we can only hope one
of the Giants pursues the development of such a product. Will it be better than a good
quality MF viewer? vs. a 3d World viewer, it will be close....but it would never match a
high quality MF optic with Strong back lighting. But IMO, it will be close enough to the
3dWorld type viewers, whereas the convenience factor will make "most of us" forget about
the amazing potential film posses...

Bill

Subject: most "natural" viewing experience yet (was ...Holy Grail of MF optic
Date: 2010-08-29 18:20:51
From: lattie_smart

Just for the heck of it, I put some slides on the light table and plunked down my pair of 10x Loreo Lubot loupes on the middle of them.

Sure, they're cheap, uncoated, plastic lens with minimal ER. BUT...they also have a "high-tech three element optical configuration incorporat(ing) a computer designed aspherical lens..."

So, putting aside my glasses and pressing my eyes into them, I have to say it was the most immersive experience I've had yet with stereo.

I have astigmatism, but often don't wear my glasses just walking around. So, it kind'a replicated that whole, unglasses experience. Glare and low-contrast wasn't so noticable. With my bare eye practically pressing into the lens, I could could scan around the image area to the natural limit of my vision, just like in real life. Straight edges looked straight, and I noticed no obvious distortion, or stretching. It felt like a completely natural, real-life viewing experience.

So, if you don't mind seeing a partial image and cleaning off the lens each time, it's a pretty fun experiment. So go ahead and be an optical heretic, no one needs to know! ;-)

Subject: Re: most "natural" viewing experience yet (was ...Holy Grail of MF o
Date: 2010-08-29 21:00:17
From: scott.youmans@scyphoto.com

Where can these be obtained?

Thanks,

Scott

--- On Sun, 8/29/10, lattie_smart wrote:

From: lattie_smart
Subject: [MF3D-group] most "natural" viewing experience yet (was ...Holy Grail of MF optics....)
To: MF3D-group@yahoogroups.com
Date: Sunday, August 29, 2010, 5:20 PM

Just for the heck of it, I put some slides on the light table and plunked down my pair of 10x Loreo Lubot loupes on the middle of them.

Sure, they're cheap, uncoated, plastic lens with minimal ER. BUT...they also have a "high-tech three element optical configuration incorporat(ing) a computer designed aspherical lens..."

So, putting aside my glasses and pressing my eyes into them, I have to say it was the most immersive experience I've had yet with stereo.

I have astigmatism, but often don't wear my glasses just walking around. So, it kind'a replicated that whole, unglasses experience. Glare and low-contrast wasn't so noticable. With my bare eye practically pressing into the lens, I could could scan around the image area to the natural limit of my vision, just like in real life. Straight edges looked straight, and I noticed no obvious distortion, or stretching. It felt like a completely natural, real-life viewing experience.

So, if you don't mind seeing a partial image and cleaning off the lens each time, it's a pretty fun experiment. So go ahead and be an optical heretic, no one needs to know! ;-)

Subject: Re: most "natural" viewing experience yet (was ...Holy Grail of MF o
Date: 2010-08-29 21:07:19
From: George Themelis

From DrT : )

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220644847827

George

From: scott.youmans@scyphoto.com

Sent: Sunday, August 29, 2010 11:00 PM

To: MF3D-group@yahoogroups.com

Subject: Re: [MF3D-group] most "natural" viewing experience yet (was ...Holy Grail of MF optics....)

Where can these be obtained?

Thanks,

Scott

--- On Sun, 8/29/10, lattie_smart <lattie_smart@yahoo.com> wrote:

From: lattie_smart <lattie_smart@yahoo.com>
Subject: [MF3D-group] most "natural" viewing experience yet (was ...Holy Grail of MF optics....)
To: MF3D-group@yahoogroups.com
Date: Sunday, August 29, 2010, 5:20 PM

Just for the heck of it, I put some slides on the light table and plunked down my pair of 10x Loreo Lubot loupes on the middle of them.

Sure, they're cheap, uncoated, plastic lens with minimal ER. BUT...they also have a "high-tech three element optical configuration incorporat(ing) a computer designed aspherical lens..."

So, putting aside my glasses and pressing my eyes into them, I have to say it was the most immersive experience I've had yet with stereo.

I have astigmatism, but often don't wear my glasses just walking around. So, it kind'a replicated that whole, unglasses experience. Glare and low-contrast wasn't so noticable. With my bare eye practically pressing into the lens, I could could scan around the image area to the natural limit of my vision, just like in real life. Straight edges looked straight, and I noticed no obvious distortion, or stretching. It felt like a completely natural, real-life viewing experience.

So, if you don't mind seeing a partial image and cleaning off the lens each time, it's a pretty fun experiment. So go ahead and be an optical heretic, no one needs to know! ;-)

Subject: Re: most "natural" viewing experience yet (was ...Holy Grail of MF o
Date: 2010-08-30 08:04:36
From: lattie_smart

I also tried it on a stereo pair cha-cha-ed with a longer focal length lens. The scene didn't seem quite as natural to me - but maybe it was also some retinal rivalry.

I haven't tried it yet on a slide taken with wide-angle lens.

I don't know why the Spud 75mm focal length shots seem so natural to me using such short FL viewing loupes. The aspheric flat field of view helps the eye roaming, but the perceived depth of objects in space seems quite normal to me. Maybe those with more expertise in these things will notice some distortion, but I can't.

I shot some old NYC street scenes with my spud on a short, Stitz tripod. The sensation of now viewing them this way makes me feel like I'm squatting there on the sidewalks, looking around. Maybe feeling like someone will walk by and give me some spare change! ("Will work for a TL-120") ;-)

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-08-31 08:45:43
From: Don Lopp

> I guess we omitted the LEEP optics, which sacrificed sharpness and
> aberration for HFOV?

Leep optics offer, a mediocre "HFOV", combined with a mediocre control
of distortion, low resolution and lots of color aberations.

> Any opinion on the Pentax 5.5x? (Lot'sa eye relief traded for
> distortion)?

> Bills' opinion: The Pentax loupe is designed for
> 35mm film. Viewing outside a 12mm image radius, > distortion
> is uncomfortable. It is a good loupe for 35mm film. The best
> off the shelf optics, that have benefited from modern design
> and glass improvements.

This Pentax 5.5X slide viewer loupe, is said to, only, cover
an image circle of 24mm. The 24mm image circle will not, even
come come close to providing an optically pleasant view of a
Realist 23mm X 24mm image. If the stereo image is even larger,
the image must be a terrific image ! I was surprised to read

If this Pentax, 5.5X loupe, at $150 each. is an example of,
the best of, "off the shelf optics", WOW.

I do not understand how this Pentax loupe could be described
as being designed for 35mm film unless the images are, taken
with a fish-eye lens that produces circular images, that are,
each, 24mm in diameter.

Regards,

DON

> Some have made old, multi-element camera lens into serviceable
> 35mm loupes - but none would be wide enough to cover a 24mm x
> 36mm stereo slide or a Realist 23mm x24mm image as we have just
> been told that the viewer is designed to cover an image circle
> with a diameter of only 24mm, whereas the 5perf stereo
> image requires a lens that will cover an image circle of about
> 33mm, not 24mm.

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-08-31 08:46:29
From: Brian Reynolds

Bill G wrote:

>
> So to go to the next step in MF viewing, you need better performing
> optics. However, small gains in optical performance come at a very
> high price in glass size, weight, barrel size and cost. To re
> produce the basic cinema experience, ~ 50 - 55 deg HFOV, requires a
> 5 - 6 element design at approx. 50 mm fl. The lens weighs about 2
> lbs each, and is about the size of your clenched fist. Of course,
> the size of the glass is also needed to control distortion and
> produce sufficient Eye Relief (ER) for Eye Glass wearers. Cost to
> make these in low volume say under 100 is about $1k each with
> machined barrels. This is Asian manufacturing....in the USA, about
> 3x this cost. Then there is shared design and prototype
> amortization. Of course a viewer would have to be designed around
> the lenses. I have several of these lenses prototyped and use them
> for my home viewing, and yes, they are a quite a treat. However, I
> accepted it is not commercially feasible to manufacture them into a
> viewer, as the viewer would be very costly, in the $3 - $4k range.
> Again, low volume kills everything. You can look at one of these
> lens designs here....

I'd offer two pieces of advice. First, use what looks good to your
eyes. Don't worry too much about being optically correct to the
smallest fraction of a wavelength. If you enjoy the view, go with it.
Improvements can be made as time and funds allow it.

Second, if you have the money, you might want to try a pair of good
quality telescope eyepieces. For example, the Tele Vue 55mm Plossl
has a 50 degree apparent field of view, 55mm focal length, 38mm eye
relief, 2 inch barrel, weights 18.1 ounces, and can be bought for
about $220 each. I don't have one, but it should easily cover a 35mm
slide, and would possibly do pretty good with MF. My Tele Vue 25mm
Plossl will definitely cover a 35mm slide, but due to the 1-1/4 inch
barrel won't cover anything larger.

<http://televue.com/engine/TV3_page.asp?id=51&Tab=EP_EPL-55.0>

--
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 |

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-08-31 09:41:27
From: lattie_smart

Actually, I think you can get a Pentax 5.5x for around $80 new.

It's funny to read online how it's either everyone's fave, or worst loupe! ;-)

There is a simple explanation for this. The tremendous eye relief was meant to enable viewing a 35mm slide from at least a few inches above the glass. From this vantage point, you can pretty much see the whole 36mm width bright and clear without pincushioning. Push your eye down for a closer look and the "walls cave in!" This is also what happens if you want to "look around" a 6x6 slide, except without the frame edges visible, you won't see the distortion right away.

--- In MF3D-group@yahoogroups.com, Don Lopp wrote:

> This Pentax 5.5X slide viewer loupe, is said to, only, cover
> an image circle of 24mm. The 24mm image circle will not, even
> come come close to providing an optically pleasant view of a
> Realist 23mm X 24mm image. If the stereo image is even larger,
> the image must be a terrific image ! I was surprised to read
>
> If this Pentax, 5.5X loupe, at $150 each. is an example of,
> the best of, "off the shelf optics", WOW.
>
> I do not understand how this Pentax loupe could be described
> as being designed for 35mm film unless the images are, taken
> with a fish-eye lens that produces circular images, that are,
> each, 24mm in diameter.
>

Subject: Lubots (was "most "natural" viewing experience yet )
Date: 2010-08-31 09:48:46
From: lattie_smart

The loreo Lubot has these specs:
Magnification: 10x Distortion Free
Lens system: 3-element achromatic Aspherical lens design
Field of view: 30mm nominal (up to 50mm by "looking around")
Eye Piece Diameter: 20mm
Eye Relief: 15mm
Working Distance: 17mm

The FOV seems pretty wide for such a tiny lens - but you have to really smudge your eyelashes in order to "look around." You may not convince friends and family to endure this kind of "optical waterboarding" but some of us will definitely find it worthwhile.

If you can endure this slight discomfort and live without the sharpness, contrast and ER of coated optical glass, it really seems very submersive. It's like scanning a real scene thru a smaller pair of glasses.

The next step would be to make a viewer with similar lens in them and a slide carrier or lensboard that could shift around at correct orientation so you can scan the whole scene. It could give digital VR a run for it's money.

And to think, I was going to eBay my pair just before discovering this!

BTW, George...do I get 10% credit for every Lubot you sell this week? ;-)

--- In MF3D-group@yahoogroups.com, "George Themelis" wrote:
>
> From DrT : )
>
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=220644847827
>
> George
>
>
> From: scott.youmans@...
> Sent: Sunday, August 29, 2010 11:00 PM
> To: MF3D-group@yahoogroups.com
> Subject: Re: [MF3D-group] most "natural" viewing experience yet (was ...Holy Grail of MF optics....)
>
>
>
> Where can these be obtained?
>
> Thanks,
>
> Scott
>

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-08-31 11:30:52
From: Bill G

Brian

> I'd offer two pieces of advice. First, use what looks good to your
> eyes. Don't worry too much about being optically correct to the
> smallest fraction of a wavelength. If you enjoy the view, go with it.
> Improvements can be made as time and funds allow it.

What looks good is not known until after prototypes are made... and
therein lies the tremendous cost of designing / producing an optic. So before an optic is
made, all you have to work with is performance models. This is why you optimize the
design, as real-world builds will rarely produce 100% of the performance you have designed.

> Second, if you have the money, you might want to try a pair of good
> quality telescope eyepieces. For example, the Tele Vue 55mm Plossl
> has a 50 degree apparent field of view, 55mm focal length, 38mm eye
> relief, 2 inch barrel, weights 18.1 ounces, and can be bought for
> about $220 each. I don't have one,

I own a pair of these..... I also own several pairs of the newer Tele
Vues 100 deg. AFOV. As well as many of the newer Bader Hyperions which incorporate
several aspherical elements in the design. One would think telescope EP's is a logical
place to turn for film loupes, as the market has been large enough to fund research for
improved products through the years. However, this is a false assumption....

Taking the TV Plossl's you mentioned... First, the AFOV you correctly state at 50 deg.
However, all Telescope EP's state AFOV based on the diameter of their image circles. When
you reduce this down to a 1.5 aspect ratio film, such as full frame 35mm, it will only
produce 39 deg HFOV. If you reduce it down to a more common 1.25 aspect ratio such as
the common 24x31 film size, the HFOV is now only 34 deg. Not so great... you are better
off with a Red Button viewer. but more importantly...

In designing any optic, the designer has a set of parameters he is trying to control. The
design process is a give n take war. You add ER, you radically increase the diameter of
the lens, you increase the viewing circle, you add distortion, you add MTF, you increase
lateral color aberations, etc. (just a few examples of the opposing variables) In
certain fields, a design parameters is less critical than others, so the designers let
that parameter drift off. In astronomical EP's, that parameter is distortion. The
reason is obvious, looking at the night sky, you desire pin point stars and high contrast.
The fact stars are not in their natural position by say 5 - 10 degrees will never be
noticed by an observer. However, when looking at film on a light box, these distortions
are very noticeable. Whats worse, due to fixed film width and varying IPD distances,
the distortion shifts in each eye, so you now introduce a new form of rivalry, which is
distortion rivalry...

But the biggest problem with using "most" telescope EP's is the fact their field stops
(the plane in which the objective lens will deliver the focussed image) is often placed
between the bottom element and the next element. This makes most astronomical EP's
unusable for film loupes. IIRC, all but the Plossly line in TV's EP have these internal
field stops.

Also, the field stop plane, based on the f ratio of the telescope will deliver a curved
focused field at the field stop diameter, (vs. film which is dead FLAT) so the EP is
designed to correct for this field curvature. However, when you introduce an image plane
which is FLAT, the EP now forces the eye to provide several diopters of accommodation at
different positions on the image radius to have a fully focussed FOV on the retina. For
many of the 50+ crowd, who have little or no accommodation remaining from presbyopia, a
sharp view over the entire FOV is nearly impossible, due to loss of accommodation.

Anyway, this is just a few of the reasons why telescope EP's make very poor film viewing
optics.... there is MANY others, but I won't bore ya... However, the Plossl design,
(not unique to TV) are probably one of the few which are usable, due to their simple
design and external field stop....

but it should easily cover a 35mm

> slide, and would possibly do pretty good with MF. My Tele Vue 25mm
> Plossl will definitely cover a 35mm slide, but due to the 1-1/4 inch
> barrel won't cover anything larger.

This limitation exists with all telescope EP's, about 25mm field stop
with 1.25" EP's and 44mm field stop Diameter with the 2" EP's....but these are often
exaggerated, as the designer lets the last 5 - 10 degrees fall in performance to maintain
very high MTF in the center viewing area....

The other major problem with telescope EP's is as the fl's get shorter, the ER becomes
much shorter... with a stationary eye, the min. ER is about 13 - 15mm, and this assumes
your cornea is smack on the glass, or within 1 mm. However, if you want to rotate your
eye, this is where the lens designs fall apart. The "center axis of rotation" in the
human eye is approx. 15mm behind the cornea, if you leave 5mm of air space between the
cornea and top glass element, you are at 20mm. Now add the distance from the eyes center
of rotational axis to the retina, ~13mm, and you have a min. 33mm of ER required to see
the entire AFOV. (Apparent Field of View in Astrononmy is the angle projected on the
retina) IF the person is wearing corrective eyewear, you must add the distance between
his cornea and the front surface of the lens, about 10mm - 12mm on avg. This pushes the
ER requirement to 43mm....i.e. for both Eye Glass (Eye Glass) wearers and Non EG users to
experience the same view when rotating the eye.

Instead, many of the larger AFOV EP designs have 12 - 15mm of ER. This is sooo short,
you are forced to move your head to the opposite side of the image circle you want to
view, too prevent the exit pupil from missing your eye completely and you experience
black-out. This is why Al Nagler for years preached the bobbing head principle to use his
eye-pieces...he was right, this is a physical means to overcome the ER shortcoming. When
you bob your head to the left, to see the right side, you loose site of the left side of
the image circle. EP's makers understood this, but they were incapable of designing an
EP with long ER and wide AFOV. Again, these are opposing forces in the design process.

For stereo viewing, we don't have the option of moving our head to the right, to see the
left side of the image, as the other eye would pull away from the glass, far from the
design condition.

Of course, with optics on a light box viewing film, there is no true exit pupil, as
produced in a compound optic like a telescope. Therefore, we can rotate our eye and
still see image area...however, the rays our eye lens are intercepting were never designed
to be hitting the eye. Each EP design requires the eye to be in ONE position to deliver
the specified performance parameters.....

This is why I saw early in my quest for "ideal viewing optics" , the only means of getting
a suitable EP for a stereo viewer for the general public (EG and non EG users) is to
design them from scratch and use all the performance characteristics required for viewing
with a wide FOV. No other optic in the market place has such stringent requirements like
a stereo viewing optic. None even close... binocular EP's are simple, as you never
rotate your eye, you simply move the binocs so the subject of interest is always in the
center of the view...we don't have that luxury.

Hope this is helpful...

Bill

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-08-31 11:56:55
From: Bill G

> It's funny to read online how it's either everyone's fave, or worst loupe! ;-)

Good point...one of the reasons is, human vision is a huge variable.
Some people can see as good as 20/10, others, 20/60... This is why when I show my Grandma
Provia 400 slides with a 35mm fl lens, she says they look identical to my Provia 100F
slides with the same viewing lenses (same taking lenses) For me, I can literally count
the grain in the ISO400 speed film, yet she sees no difference... So if your vision is
not the limiting factor, you can get away with some pretty crappy optics and find them
excellent. This is one of the reasons you can get so many extreme opinions on optics.

The other HUGE variable is light levels. With normal low brightness light
boxes, the pupil is dilated to 5 - 6mm (wider for young crowd), and at this wide iris
opening (apt.) human vision is extremely poor. The eye is a lens, no different than a
camera lens. All camera lenses produce great MTF at a given aperture opening, and poor
performance at a different aperture, the human eye is the same. In bright light, forcing
a 2 - 2.5mm iris diameter opening, visual acuity can increase four fold.... so simply
adding light levels will make many of the optical shortcomings become very obvious.

I designed a light box that will force 2mm eye pupils, about 50k foot
candles of light. This forces the eye to dilate down to the high MTF position, and the
eye becomes razor sharp and does more to improve the view than using better optics alone.
Pointing a 3dWorld STL viewer directly at the sun will give you a feel for how effective
this is.

> There is a simple explanation for this. The tremendous eye relief was meant to enable
> viewing a 35mm slide from at least a few inches above the glass.

A few inches of ER? That is > 50mm of ER? Other than Rifle scopes,
which have < 5 deg FOV, I have not seen any optic with a decent FOV to have this level of
ER. As I mentioned in the previous post, ER and wide HFOV are the hardest two variables
to achieve in any optic design. They are opposing forces...

From this vantage point,

> you can pretty much see the whole 36mm width bright and clear without pincushioning. Push
> your eye down for a closer look and the "walls cave in!" This is also what happens if you
> want to "look around" a 6x6 slide, except without the frame edges visible, you won't see
> the distortion right away.

try looking at some grid paper (graph paper) on a light box, then you
will get a better feel for the true distortion that actually exists. The brain will try
to correct distortion in images, but will not attempt to correct a square grid pattern.

And yes, as you move the eye down below the ER position, you have
essentially negated the design.... your eye is now in locations where the rays your eye
lens is intercepting were never designed to be on your eye lens. Performance falls-off
exponentially. But, I understand the desire to go IMAX... :-)

Bill

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-08-31 13:27:51
From: lattie_smart

This issue with the Pentax 5.5x was never about clarity, contrast or sharpness (it seems fine and it also has a generous focusing range).

It's all about distortion. I think it was optimally designed to view a whole slide naturally from a few inches above. This gives a quick, casual, stress-free preview of slides without neck or eyestrain. Don't forget, this is a relatively unique loupe, whose visible glass width is nearly 2 inches across the eyepiece! It was designed for anything but scrunch n' squint!

While specs say "Extra Long eye relief - 0.6 inch (14mm)" I can see a full frame slide clearly from much higher, with only the corners clipped.

I notice that when I pull my head back a little further, I start to see obvious barrel distortion on the slide edges. When you slowly lower you eye, the edge snap back into square...then slowly start to concave as you keep lowering your eye.

It's a natural instinct to want to get down closer to "really look around at all the detail." But, the slide image itself just doesn't grow bigger that way. You're only seeing more blank area around the slide at the edges, with the slide showing definite pincushioning.

If anyone is interested in buying these things to experiment with, PM me.

--- In MF3D-group@yahoogroups.com, Bill G wrote:
>
>
>
> > It's funny to read online how it's either everyone's fave, or worst loupe! ;-)
>
>
> Good point...one of the reasons is, human vision is a huge variable.
> Some people can see as good as 20/10, others, 20/60... This is why when I show my Grandma
> Provia 400 slides with a 35mm fl lens, she says they look identical to my Provia 100F

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-08-31 16:38:09
From: Bill G

Lattie

> It's all about distortion.

IF it weren't for distortion, there would be some awesome optical stereo
viewers on the market right now, and your search would be over :-) Wide angular FOV and
distortion are opposing forces in optics...this is true in viewing lenses, camera lenses,
binoculars, etc. Hence the price of a highly corrected WA taking lens being about 4x
the price of a equally corrected normal fl taking lenses... which have about half the FOV.

> While specs say "Extra Long eye relief - 0.6 inch (14mm)" I can see a full frame slide
> clearly from much higher, with only the corners clipped.

14mm is a lot more realistic vs. 50mm+ you quoted earlier. As you pull
away from the lens, the viewing circle becomes smaller, this is true with all loupes...
when you say "only the corners clipped" if you measure this, you will see it becomes a
significant % of the image radius.

> It's a natural instinct to want to get down closer to "really look around at all the
> detail." But, the slide image itself just doesn't grow bigger that way.

It actually does get bigger...but not by the amount you would think. The
nominal fl of any loupe is stated at the design condition, which is at the ER position
ONLY, and when the loupe is focused to infinity.

The "effective fl" is the actual fl of the loupe when you change focus
position and/or change the eye placement relative to the ER position....obviously closer
to the glass will increase the effective fl. Close focusing will also lower the fl.
And this is one of the reason I struggled with ever making lenses on a commercial basis.
Because if EG wearers remove their corrective eyewear to use a viewer with ind.
focussing lenses, they can correct their refractive errors (non astigmatism errors)
through the loupes. However, there is a major drawback to this when stereo viewing (vs.
single eye loupe use)... the effective fl's of the two lenses alter drastically vs.
leaving the corrective eyewear on and having both loupes focused at the same focus
distance. As a result, you enter into a new area of rivalry, magnification rivalry.
This is why a viewer for the general public needs to have looong ER, so users can see the
entire view while leaving on their corrective eyewear... more than half the gen.
population wears corrective eyewear. I have designed / built these loupes, some with
37mm of ER (seeing the corners)..and for MF, the glass size becomes huge.... with barrels
almost 4 lbs per lens...

The more interesting observation you posted the other day, was about how
your eye had to swivel the full 90 deg. to see the left / right edges with your cornea
nearly touching the glass. This is true, you are artificially increasing the HFOV with
only a slight change in the fl. A bit of optical trickery :-) However, two
problems... you are viewing "stray" rays...i.e rays that are not fully corrected, as those
rays only exist at the ER position... and as you noticed, the glass will quickly be full
of eyelash gunk... muddyin'up the views. The solution is, ultra long ER with wide HFOV
all rolled up into a single optic.

Bill

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-08-31 21:08:56
From: lattie_smart

I see the "gunk" as the price of admission ;-)

Added ER would be welcome, BUT, I can't help but see a trade-off there. You're gaining eye-space, but losing more of that "VR Reality" by seeing more of the eyepiece in your peripheral vision whilst scanning the scene...

> The more interesting observation you posted the other day, was about how
> your eye had to swivel the full 90 deg. to see the left / right edges with your cornea
> nearly touching the glass. This is true, you are artificially increasing the HFOV with
> only a slight change in the fl. A bit of optical trickery :-) However, two
> problems... you are viewing "stray" rays...i.e rays that are not fully corrected, as those
> rays only exist at the ER position... and as you noticed, the glass will quickly be full
> of eyelash gunk... muddyin'up the views. The solution is, ultra long ER with wide HFOV
> all rolled up into a single optic.
>
>
> Bill
>

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-08-31 21:52:45
From: Bill G

> Added ER would be welcome, BUT, I can't help but see a trade-off there. You're gaining
> eye-space, but losing more of that "VR Reality" by seeing more of the eyepiece in your
> peripheral vision whilst scanning the scene...

Lattie, with the ideal lens design, you can have the VR
experience, (say 80 - 90 deg HFOV) with the ER required to get the eye lashes off the
glass. (not too mention near zero distortion and ultra high contrast with un noticeable
aberrations) That was my point....

You just can't do it with off-the-shelf surplus lens for $15. Again, this
goes back to the Holy Grail of viewing optics :-)

BTW, did you know that less than 1/3 of our depth perception comes from
the stereo component (binocular disparity)? Your quest for immersiveness is worth more
IMO than the stereo component. Of all the 3d I have viewed in my life, nothing has ever
given me more of a VR experience than a 180 deg movie shot and projected in 2d. It blew
away all these 3d products for the "I am there" experience. They exist in some of the
theme parks or around national parks. They provide you hand rails, as you are standing,
and if you don't hold on, you will fall, now that is what I call IMMERSIVE! And it's all
in 2d. Motion provides continuous parallax cues to our brain, without binocular
disparity. Remarkably, our brains "get it". Of course, these are million dollar +
set-ups. However, this same experience might soon be available once OLED technology
advances a bit further and we can view motion images in a half cylinder. Just imagine, a
full 150 - 180 deg image with motion and sound! So the 3d future looks bright, it's just
a bummer having to wait for all this to develop.... :-(

Have you viewed the Plasma 3dtv's yet? If you view at a
distance equal to the screens horiz dimension, you will have a 53 deg HFOV... not bad,
assuming the content is fitting for this viewing distance. Combine this with sound,
motion and non-stop content with no effort on your behalf, vs. one view in, one view
out.... That is the power that digital 3d viewing has. ohh yeah, and others can see
what your seeing at the same time, and comment on it, without passing a viewer around the
room :-) This is why 3d optical film viewers are on the way out...unfortunately....

Bill

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-09-01 06:52:45
From: lattie_smart

Bill, I'm getting an accelerated education from you, for sure! ;-) Everytime I try to understand optical diagrams, I kick myself for not paying more attention in math and geometry classes! When I win Powerball, you and I will make a set of your theoretical lens for just ourselves! ;-)

I did the Disneyland, surround screen, firetruck handrail thing as a kid, and yes, I was excited (but proudly retained full bladder control!) ;-) .

But, I guess my 3D and immersion aesthetic is more about "thereness" and contemplative "stillness" more than action or suspension of belief.

Like George says when preferring digital, I enjoy taking a lot of casual, "people" shots, often with flash. But, instead of just getting a fast 3D effect and simultaneously sharing it with your friends - I'm more for quiet, intense, viewer study. Yep, it's just a shot of people at a party. But I can go back and notice something new each time in my viewer. The fabric, carpeting, a stray glass, other people over a shoulder - all frozen in space to be discovered. None of it nearly as interesting to me in flattie-vision. Cities are even better. They reveal another hidden person, obscured printed images or new sidewalk details with each study!

I once went thru a "stereo paparazzi" phase - taking shots of stars and celebs from my Boomer childhood. They're all much older, wrinkler, but much more accessible now! ;-) It's like having my own wax museum! I can practically count the follical implants in an aging stars scalp, the crow's feet in a fading starlets eyes. I got relatively close shots at a Jimmy Carter book signing. You can see the fine thread count in his suit and tie, and practically tell what he had for dinner in his trademark, toothy grin! ;-)

Frivolity aside, what I'm saying is all of this can't be accomplished with big screen, motion 3D or flickery, digital quickies. These kind of pleasures are only accomplished in sharp film images. I think we have at least another five year's wait for an *affordable* digital taking and viewing system that is comparable.

The limit to all this is that you're always aware that you're

>viewing a scene
>behind a window
>through an aperture.

The eye-squish immersion method is just an alternative to a full view of sharp details. You definitely sacrifice some comfort, sharpness, and geometric correctness. But now there is NO window, and virtually no aperture getting in my way.

When I view my Times Square night scene, the shot is hazy from the mist, lights glare in my un-shaded Spud lens, and everything has reciprocity grain from my exploratory exposures.

As I slide the loupes over to a corner of it, I am only looking at a bike rack in the foreground - half-shadowed, covered with Gotham grime and banal as heck.

But that bike rack is fully present
...in full depth
.....in my full field of vision
.......IT'S THERE
..........and I'M THERE.

And it's beautiful.... ;-)

--- In MF3D-group@yahoogroups.com, Bill G wrote:
>
>
> > Added ER would be welcome, BUT, I can't help but see a trade-off there. You're gaining
> > eye-space, but losing more of that "VR Reality" by seeing more of the eyepiece in your
> > peripheral vision whilst scanning the scene...
>
>
>
> Lattie, with the ideal lens design, you can have the VR
> experience, (say 80 - 90 deg HFOV) with the ER required to get the eye lashes off the
> glass. (not too mention near zero distortion and ultra high contrast with un noticeable
> aberrations) That was my point....
>
>
> You just can't do it with off-the-shelf surplus lens for $15. Again, this
> goes back to the Holy Grail of viewing optics :-)
>
>
> BTW, did you know that less than 1/3 of our depth perception comes from
> the stereo component (binocular disparity)? Your quest for immersiveness is worth more
> IMO than the stereo component. Of all the 3d I have viewed in my life, nothing has ever
> given me more of a VR experience than a 180 deg movie shot and projected in 2d. It blew
> away all these 3d products for the "I am there" experience. They exist in some of the
> theme parks or around national parks. They provide you hand rails, as you are standing,
> and if you don't hold on, you will fall, now that is what I call IMMERSIVE! And it's all
> in 2d. Motion provides continuous parallax cues to our brain, without binocular
> disparity. Remarkably, our brains "get it". Of course, these are million dollar +
> set-ups. However, this same experience might soon be available once OLED technology
> advances a bit further and we can view motion images in a half cylinder. Just imagine, a
> full 150 - 180 deg image with motion and sound! So the 3d future looks bright, it's just
> a bummer having to wait for all this to develop.... :-(
>
>
> Have you viewed the Plasma 3dtv's yet? If you view at a
> distance equal to the screens horiz dimension, you will have a 53 deg HFOV... not bad,
> assuming the content is fitting for this viewing distance. Combine this with sound,
> motion and non-stop content with no effort on your behalf, vs. one view in, one view
> out.... That is the power that digital 3d viewing has. ohh yeah, and others can see
> what your seeing at the same time, and comment on it, without passing a viewer around the
> room :-) This is why 3d optical film viewers are on the way out...unfortunately....
>
>
> Bill
>

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-09-01 09:00:20
From: Bill G

Lattie

> Bill, I'm getting an accelerated education from you, for sure! ;-) Everytime I try to
> understand optical diagrams, I kick myself for not paying more attention in math and
> geometry classes! When I win Powerball, you and I will make a set of your theoretical lens
> for just ourselves! ;-)

You sure are right, visual optics is a mixed bag of math, physics and
solid foundation of human vision (and stereo vision). It's the mix of all 3 of these
disciplines that is unique to this field. Which is why you will never find a book on
stereo optics... again, unfortunately....

Remember, many of the designs I have successfully designed and BUILT, they are
not theoretical. I use them on a regular basis.... as well as the custom made light box
which has an array of LED's producing 50,000 foot candles of light, and draws 800 watts of
power. I just never made the optics commercially available due to the outrageous cost to
reproduce them in low volume. I started out thinking I would, but that was 7 years ago,
b4 digital technology reared its ugly head :-(
I guess - it' a bad case of - VERY bad timing....

> But, I guess my 3D and immersion aesthetic is more about "thereness" and contemplative
> "stillness" more than action or suspension of belief.

I think both have tremendous merit, I still love stills (excuse the
pun :-). The point being, that "being there" includes sound and motion...even if its
subtle, and digital will soon offer that. But regardless, its truly remarkable what can
be done with film and optics, fully agreed....

>
> Like George says when preferring digital, I enjoy taking a lot of casual, "people" shots,
> often with flash. But, instead of just getting a fast 3D effect and simultaneously sharing
> it with your friends - I'm more for quiet, intense, viewer study. Yep, it's just a shot of
> people at a party. But I can go back and notice something new each time in my viewer. The
> fabric, carpeting, a stray glass, other people over a shoulder - all frozen in space to be
> discovered. None of it nearly as interesting to me in flattie-vision. Cities are even
> better. They reveal another hidden person, obscured printed images or new sidewalk details
> with each study!

Agreed... and there is a handful of us on this list who share your
position in this regard. But the masses will be happy with a Fuji W3 and the newer
digital displays that might be here in the next year or two. They much rather trade some
of that resolution for simplicity of both taking and viewing, and most importantly,
sharing the images. Makes sense...

>
> I once went thru a "stereo paparazzi" phase - taking shots of stars and celebs from my
> Boomer childhood. They're all much older, wrinkler, but much more accessible now! ;-) It's
> like having my own wax museum! I can practically count the follical implants in an aging
> stars scalp, the crow's feet in a fading starlets eyes. I got relatively close shots at a
> Jimmy Carter book signing. You can see the fine thread count in his suit and tie, and
> practically tell what he had for dinner in his trademark, toothy grin! ;-)

coool.... I think this is where stereo photogrpahy is unique...
35mm or MF? You never mention which format you shoot most often? I have drifted to
35mm more often due to the razor sharp optics, (you can open up 2 stops and have the same
DOF as MF) 2 stop faster shutter speeds and the hand-hold-ability factor can't be beat
.... Since I get the same HFOV viewing the 35mm slides vs. the MF, I have become partial
to 35mm stereo. But when the scene is dead still, I still bring out the MF guns... If the
scene is really still, I shoot cha cha 8x10.

>
> Frivolity aside, what I'm saying is all of this can't be accomplished with big screen,
> motion 3D or flickery, digital quickies. These kind of pleasures are only accomplished in
> sharp film images. I think we have at least another five year's wait for an *affordable*
> digital taking and viewing system that is comparable.

I sort of agree....the "wild card" though is the OLED displays.
If they ever deliver on their promise, you will be able to purchase a display that is
rolled up like a roll of wallpaper. Unroll it in any shape you want. Now, you can have
the fully immersive 180 degrees you desire and resolution in the 16MP range...which will
surely exceed the best MF film... so then, you will have to shoot with MF digital backs
with 100MP sensors to take advantage of all this display potential !

>
> The limit to all this is that you're always aware that you're
>
> >viewing a scene
> >behind a window
> >through an aperture.
>
> The eye-squish immersion method is just an alternative to a full view of sharp details.
> You definitely sacrifice some comfort, sharpness, and geometric correctness. But now there
> is NO window, and virtually no aperture getting in my way.

Understood and agreed. Your desire for wide FOV trumps everything
else... you are not the first one to crave this, so many of us can surely appreciate your
desire. But like everything in life, you get spoiled very quickly once you "see" better.
But with using off-the-shelf optics, you have created a best-case scenario for yourself...

> But that bike rack is fully present
> ...in full depth
> .....in my full field of vision
> .......IT'S THERE
> ..........and I'M THERE.
>
> And it's beautiful.... ;-)

Having fun is what its all about, and that you seemed to have
accomplished... Your "cornea on the glass" technique will be your own "private Idaho".
I doubt the avg person could ever stomach the levels of distortion rivalry that occurs,
but that is of no concern if you never want others to experience it... it's the desire to
bring share the art-form to the general public, ..... that's where some of us have
fall'en off the cliff :-) Also, without you knowing it, you seem to have tremendously
high threshold rivalry levels. I know i could never stomach some of your viewing
techniques. This is another problem in advancing the field... most enthusiast have
tremendous visual thresholds for stereo errors, whereas the general public does
not...heck, that's why they became enthusiast in the first place :-)

BTW, as a side note, I have developed other viewing methods which are equally intriguing
... one is using two 30" displays (4MP each) with an 8 lb custom designed / built 90 deg.
prism between the two... its cramped, a bit claustrophobic, but 55 deg HFOV when you fill
the 16:9 aspect ratio. This certainly is NOT commercially feasible, specially
considering the weight of the displays alone is nearly 80 lbs, not counting the control
system for display alignment. But it blows away the flicker approach of the 3d tv as you
get the full magnitude of brightness and contrast. But unfortunately, this will always
be limited for the truly insane.

After my short fl optics approach, I altered my approach, and wanted to rid the optic
quandaries that accompany very short fl optics. I wanted the same view, with simple
optics (like you do :-) The solution is, is long fl optics combined with much larger
images. Yep, you can actually produce very low cost optics (even simple doublets) that
are equally effective as these Mega costly optics which have the HUGE benefit of viewing
"out-of-camera film", but end up being about these sizes....

http://www.pbase.com/bglick/image/100729033

I have successfully prototyped long fl doublets and triplets that can deliver the same
PUNCH (HFOV, resolution, MTF and ER) as the Mega optics required for viewing the film
direct. And since they are simple optics, they have relatively low cost. The only
downside is, the viewer becomes a massive contraption, as you must incorporate mirrors and
the capacity to hold very large back lit transparencies. I have designed them to support
film as small as 4x5 and transparency views (Fuji Trans) as large as 14" wide.

If you think viewing film "out-of-the camera" is good, you would be blown-away at larger
transparencies with custom optics for this purpose... why? Fuji Trans uses the same dies
as Fuji Provia film, and the resolution potential of the Fuji Trans is MUCH greater than
film, as it holds about 1/2 the resolution of film, but the final image size is 7x
greater.... so a min. of 3 - 4x the potential resolution on the retina, assuming you can
capture this much resolution...

and film grain? What is that? The human eye can not resolve film grain at 250mm viewing
distances... The best of all worlds for viewing stereo film. Great for museums, but
not much else. The contraption becomes huge, and its extremely cumbersome to take images
in and out. I considered a multi view system, which is feasible, but lost interest, as
these become massive mechanical contraptions. The I.Q. beats anything I have every seen
(or probably ever will see), but in the end, you trade the cost of ultra expensive optics
for very expensive and large mechanical contraption. Not too mention, the cost to bring
each image from 35mm or MF to a large transparency. Again, fine for museums, but not for
the avg. hobbyist.

Bill

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-09-01 10:48:24
From: lattie_smart

>
> coool.... I think this is where stereo photogrpahy is unique...
> 35mm or MF? You never mention which format you shoot most often? I have drifted to

99% 35mm, now re-igniting MF a little more. It's great to just swallow up the whole space in 6x6 chunks! But cumbersome. It's still maddening to know that the MF slide grain can take a much bigger magnification than the 3x(?) 3D World provides. My 10x loupe immersion technique just gives another way to appreciate all the scenery.

>
>
> I sort of agree....the "wild card" though is the OLED displays.
> If they ever deliver on their promise, you will be able to purchase a display that is
> rolled up like a roll of wallpaper. Unroll it in any shape you want. Now, you can have
> the fully immersive 180 degrees you desire and resolution in the 16MP range...which will
> surely exceed the best MF film... so then, you will have to shoot with MF digital backs
> with 100MP sensors to take advantage of all this display potential !

I think when this kind of stuff gets to the average consumer level, they'll already have holographics or other new tech developed.

>
>
> Having fun is what its all about, and that you seemed to have
> accomplished... Your "cornea on the glass" technique will be your own "private Idaho".
> I doubt the avg person could ever stomach the levels of distortion rivalry that occurs,

I must insist that I notice no distortion thru the aspheric lens - nothing linear anyway. It feels very natural to me, (except for the eyelash folds). I'm thinking of getting infinity-point contact lens (corrected for my near-sighted astigmatism)so I can bring up the sharpness a little. That would also mean I wouldn't need to screw the loupes all the way down for focus - which might also mean a little bigger FOV?

>
> BTW, as a side note, I have developed other viewing methods which are equally intriguing
> ... one is using two 30" displays (4MP each) with an 8 lb custom designed / built 90 deg.
> prism between the two... its cramped, a bit claustrophobic, but 55 deg HFOV when you fill
>

>

> each image from 35mm or MF to a large transparency. Again, fine for museums, but not for
> the avg. hobbyist.
>

I've fantasized about those big trans slides too! :-) 'm thinking with large screen displays or transparencies, you could eliminate glass magnification and just go with the 1/2 flipped pair and a big, front surfaced mirror (ala John Hart's display ideas)?

LS

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-09-01 14:40:11
From: Bill G

> I must insist that I notice no distortion thru the aspheric lens - nothing linear anyway.

did you view graph paper yet? let me know when you do....

> It feels very natural to me, (except for the eyelash folds). I'm thinking of getting
> infinity-point contact lens (corrected for my near-sighted astigmatism)so I can bring up
> the sharpness a little. That would also mean I wouldn't need to screw the loupes all the
> way down for focus - which might also mean a little bigger FOV?

No, the opposite, less FOV. The closer your eye gets to a subject,
the wider the projected image is on your retina. The further you get away from a
subject, the smaller the subject projects on your retina.

But nonetheless, there is NOTHING that would improve your stereo viewing
more than correcting your astigs via contact lenses. It's too bad the bulk of the
population never went to contact lenses, it would solve some of the major issues with
stereo optical viewing for the gen. population.

> I've fantasized about those big trans slides too! :-) 'm thinking with large screen
> displays or transparencies, you could eliminate glass magnification and just go with the
> 1/2 flipped pair and a big, front surfaced mirror (ala John Hart's display ideas)?

Well, I pursued this as well.... if you don't need such wide HFOV you
crave, its a "good" approach....however, once the HFOV increases above 30 - 40 degrees,
the polarization becomes less effective, as the ray angles are pre set for one position
only. I had a proposal from a company to design custom polarizers / beamsplitters to
solve this problem, but in the end, I just could not take on another 12 month project with
design engineers, prototyping, mechanical builds, etc. etc.

The reason I say its "good" and not great is.... the light losses with the polarization
can be as high as 75%.... But, with the 90 deg mirror system, there is NO light
losses... the potential gains in this custom designed polarized approach would not be
sufficient enough to warrant the light losses and ultra high levels of light required to
overcome the light loss for back lit images. If you want an off-the-shelf solution, they
are available...

http://www.planar3d.com/3d-products/sd2620w/

Bill

Subject: Re: The quest for the Holy Grail of MF optics....
Date: 2010-09-01 15:48:21
From: lattie_smart

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

> > I must insist that I notice no distortion thru the aspheric lens - nothing linear anyway.
>
>
> did you view graph paper yet? let me know when you do....
>
>

Yep, just now - I only see a *very* slight linear-perspective convergence of the lines as they fade from view - just as distant lines would do in reality! *Maybe* just the slightest hint of them also "going over the globe" at the very far, dim edges. But no warping, pinching or bulging.

It's a pretty impressive little loupe - for "cheapo plastic!" You really need to get your hands on one! ;-) (Maybe re-doing it's aspheric, 3 element, plastic design in coated, optical glass would be prohibitively expensive.)

>
>

That would also mean I wouldn't need to screw the loupes all the

> > way down for focus - which might also mean a little bigger FOV?
>

> No, the opposite, less FOV. The closer your eye gets to a subject,
> the wider the projected image is on your retina.

I kinda thought of that too...but I was being optimistic!

>
> But nonetheless, there is NOTHING that would improve your stereo viewing
> more than correcting your astigs via contact lenses. It's too bad

I once had a Pearle vision guy make me a tiny, round prescription lens set to insert over some 10x telescope eyepieces for my attempt at an "ultimate" Viewmaster viewer - years ago. It kinda worked OK. I never like the bother of contacts, but I may try again just for better viewing.

>

>
> Well, I pursued this as well.... if you don't need such wide

HFOV you
crave, its a "good" approach....however, once the HFOV increases above 30 - 40
degrees,
the polarization becomes less effective, as the ray angles are pre set for one
position

Actually I was referring to something like John Harts Mirscope - no polarization involved, I believe. If you could light up, say, a 20x30 transparency on each side of a large mirror, then focus your unaided eyes close enough naturally...it could be interesting.

>

Subject: Loreo loupe comparative review...
Date: 2010-09-01 17:47:52
From: Bill G

Lattie

> It's a pretty impressive little loupe - for "cheapo plastic!" You really need to get your
> hands on one! ;-) (Maybe re-doing it's aspheric, 3 element, plastic design in coated,
> optical glass would be prohibitively expensive.)

I do own this loupe.... I bought it many years ago when they
introduced it. I just dusted it off after your recent enthusiasm over it. I tested it
against some of my custom loupes, some Astronomy EP's, Rodenstock loupes, Schneider loupes
and some small doublet viewer lenses etc.

First, let me preface my statements with .... we all don't have equal
vision, so its not uncommon to get different reactions from different people regarding
visual optics. Also, we all have different references, so a different comparative base
makes a huge difference when evaluating optics. Although my eyes have aged somewhat, I
am holding at 20/15 in both eyes, with no correction required other than presbyopia
correction, for near subjects...

First, the loupe is mis labeled at 10x magnification, I did a crude fl test on it, I would
rate it closer to 7.5x when focused at infinity. Huge difference. Next I tested it on
graph paper, massive field curvature.... you are accurate when you mentioned no lateral
distortion (within the viewing circle). Field curvature is a 2nd order distortion which
is less obvious when looking at film, hence why the designer traded lateral distortion for
field curvature... in other words, the center of the graph is bulging upwards, towards my
eye. It's quite extreme.

ON a scale of 1 - 10, 10 being the best, for MTF (contrast transfer from film to retina),
I would rate it a 2. 10 being my custom loupes, Rodenstock 4x and Schneider 6x....which
transfer about 90% of the films contrast through the loupe...the Loreo may be in the 25%
MTF range in the bulk of its image radius. MTF is what makes you say WOW when looking at
a back lit image. Our visual system senses contrast as sharpness (long story)

The Viewing image circle at the ER position is about 35mm.... so it surely can only be
used for 24x30 film at its max. Your nearsightedness is allowing you to perform tricks
no one would be capable of...

Chromatic aberations are strong, lateral color fringing is the culprit. I have some test
targets I use for this test... its OK till about 40% out on the image radius... then
starts falling apart...

I put an Edmunds back-lit test target under it, the best I could resolve was about 30
lp/mm in the very center and 15 lp/mm at the 50% image radius point. A high quality
loupe or an astronomy EP of the same fl will resolve at least 2x this, and further out on
the image radius.

Bottom line.... if this was the loupe that introduced me to stereo, I
would have had ZERO interest in the hobby....and probably would have never fallen off the
edge of the cliff designing new optics.... (now I kinda wish it was my first peek at
stereo, damn it :-)

In all fairness, the loupe was like $15 IIRC, and for that price, no one
can complain, instead I wanted you to know how it performs for me, against other optics of
similar fl. sorry.... :-(

As a point of comparison, I compared this loupe against an RBT STL
viewers I bought with about 50mm fl, viewing 24x31mm pairs... these are glass doublets,
the viewers were like $30 each.... the RBT blows-away the Loreo, and $30 included the
entire STL viewer. But as luck would have it, I bought all the stock from Berezin a few
years ago, (maybe 20?) and the viewers were never made again - what a bargain! I gave
all 20 away as gifts... I think I have one remaining... had I known they were never to be
made again, I would saved more!

As a side note... plastic lenses can be every bit as sharp as glass lenses.
The biggest problems with plastic is changes in temp can change the refractive index of
the plastic and it scratches easily. Quality coatings are only for anti-reflectivity,
not a big issue with stereo viewing. Assuming the sides of the elements are properly
darkened, as well as the space between the elements. I have used the same lenses coated
and un-coated, sometimes I can't tell them apart. Of course when you have 5+ element
lenses, now you have more surfaces that can reflect light, and the coatings become more
important. Plastics are easier to make in aspheres...

If you want a good pair of 35mm film loupes off-the-shelf, the only ones I would recommend
is the Schneiders 6x aspherics.... Its the best 35mm loupe made today, you can jury rig
two together and have a very good 35mm viewer. MTF is very good, distortion on all axis
is probably under 2%, barely perceivable. The fl once again is exaggerated, but maybe in
the 45mm range, or 5.5x mag. vs. the 6x the advertise, close enough. ER barely good
enough, be sure to get your contact lenses :-) You seem to be in NYC, stop by B&H or
Adorama, bring some film and the Loreo loupe, put them side by side on a light box...and
tell me what you think...

Bill

Subject: Re: Loreo loupe comparative review...
Date: 2010-09-01 20:07:28
From: lattie_smart

OK, mea culpa...You may be right about my "near-sighted advantage." Maybe everyone should get laser surgery to emulate my crappy eyes! ;-)

I screwed the loupe all the way out, where I'd get the sharper view with glasses on - and you're right, w/ or w/o my glasses, there's bulge there! (Plus, with them on, I can't "look around" at all!)

Screw it all the way back down, check again - wide, straight and square nearly all the way!!!! So, for those out there who grew up reading comic books in the dark after bedtime...these loupes may be for you! Maybe I'll pass on the contacts!

Now, beyond the perceived linear quality, I know that cheapo plastic lens can't compete with coated optical glass. No way. 'Course, my NYC shots were taken with a less modded Spud on a drizzly, hazy day - so contrast and sharpness wasn't much there to begin with! Like I mentioned before, the loupe view is like what I would typically see walking on the street without my glasses on (which is often)!

Since we opened the loupe can 'o worms here....any opinions on the Schneider 10x aspherical loupe?

----------------------
(BTW, I never stopped in B&H while up in NYC. But on the day of my Spud shots, I did stop into Adorama to rent a Horizont camera. It was like carrying two toasters around all day! I even tried panoramic cha-chas with it. "Tried" being the operative word here ;-) )

Subject: Re: Loreo loupe comparative review...
Date: 2010-09-01 22:02:09
From: Bill G

> Since we opened the loupe can 'o worms here....any opinions on the Schneider 10x
> aspherical loupe?

Yes, I have it.... it is 3 elements, no aspheres and a true 25mm fl...
the viewing circle is best suited for maybe 24x24mm film size.... and simply put, the view
is very poor, low contrast, hideous ER, and distortion that is beyond terrible. This is
what happens when you try to use only 3 elements to correct such a high magnification
lens. This loupe is really designed for close inspection, focusing on the very center
of the image area, maybe a viewing circle with a 15mm diameter. For stereo, it's a total
bust.

OTOH, the Schneider 6x aspherical loupe with 4 elements... and
considering it has an ashpere, the loupe is on par with a 5 element all-shperical loupe.
It has good ER, maybe 15 -17mm, with your lashes off the glass, you can see a full 24x33
frame. Contrast is superb, distortion is nill... as I mentioned previously, this ONE
loupe, a late entry into the loupe game, was the only loupe that benefited from the huge
increase in design capabilities that came along in the late 90's and early 2000's. The
only loupe I own that outperforms this loupe are my custom made loupes, and even then,
the gains are only in the area of ER, and slightly greater HFOV... (35mm fl, for 46 deg
HFOV on slightly smaller film) I almost settled on this Schneider design b4 starting
designing my custom designs.... it was that good... 10mm more of ER, and it would have
been a slam dunk.

http://www.schneideroptics.com/pdfs/photo/LoupeData.pdf

If you shoot full frame 35mm, and use the RBT mounts from Jon Golden, they are 33mm wide,
which will produce 43 deg HFOV with NO distortion, virtually no chromatic aberrations and
excellent contrast. Compare this with 3dWorld MF viewer, at 75mm fl and 52mm wide film =
38 Deg HFOV. So it exceeds the HFOV of MF. Impressive, huh.

If you have SHARP 35mm taking lenses, I would say these 6x loupes with 35mm
film (considering how fine grain the chrome film is today) is in a dead heat with MF views
in the 3dWorld viewer. Slightly less grain in the MF, a tad more sharpness of course,
but less HFOV. Yep...but the the convenience and low cost of 35mm is tough to beat, and
this is coming from a die-hard MF stereo guy :-) I never shot candids, till I got my
first RBT 35mm stereo camera.... now i love it! There is some awesome RBT full frame
35mm stereo cameras with razor sharp modern optics that would make a perfect match. Many
are early 2000 vintage.

What 35mm stereo camera do you shoot with now?

Anyway, don't take my word for it, stop down to B&H, they will take a pair of Schneiders
out for ya, bring some stereo views and have a peek at how awesome a 35mm viewer can be!

Bill

Subject: Re: Loreo loupe comparative review...
Date: 2010-09-02 07:58:42
From: lattie_smart

Hmmmm...the cost for a Schneider 6x pair would exceed a Combi lens set, but if it can compete with MF....Hmmmm. Can the lens housing be easily removed from the base for schleping into a viewer?

I, (unsurprisingly ;-)) , prefer an underdog 35mm stereo camera! I'm hesitant to say what it is, because I'm still looking for cheap fixer-uppers on eBay. Let's just say that it's imported lens are only triplets, but still beat the pants off of most other classic stereo cameras I've seen! Knowledgeable stereographers have mistaken it's output for a 2.8 or Custom. But it's definitely not. ;-)

Just got another fixer-upper bargain of sorts - a French Hectron w/twinned FG-20s and 50mm Series E Nikon lens. I want to swap them out for some 35mm lens. Short of an RBT, I don't think the lens performance will be matched by other dedicated stereo cameras. ;-)

Now...I wonder if the Nikon-Hectron teamed with the Schneiders would dissuade me from saving up for a TL-120?

--- In MF3D-group@yahoogroups.com, Bill G wrote:
>
>
> > Since we opened the loupe can 'o worms here....any opinions on the Schneider 10x
> > aspherical loupe?
>
>
> Yes, I have it.... it is 3 elements, no aspheres and a true 25mm fl...
> the viewing circle is best suited for maybe 24x24mm film size.... and simply put, the view
> is very poor, low contrast, hideous ER, and distortion that is beyond terrible. This is
> what happens when you try to use only 3 elements to correct such a high magnification
> lens. This loupe is really designed for close inspection, focusing on the very center
> of the image area, maybe a viewing circle with a 15mm diameter. For stereo, it's a total
> bust.
>
>
> OTOH, the Schneider 6x aspherical loupe with 4 elements... and
> considering it has an ashpere, the loupe is on par with a 5 element all-shperical loupe.
> It has good ER, maybe 15 -17mm, with your lashes off the glass, you can see a full 24x33
> frame. Contrast is superb, distortion is nill... as I mentioned previously, this ONE
> loupe, a late entry into the loupe game, was the only loupe that benefited from the huge
> increase in design capabilities that came along in the late 90's and early 2000's. The
> only loupe I own that outperforms this loupe are my custom made loupes, and even then,
> the gains are only in the area of ER, and slightly greater HFOV... (35mm fl, for 46 deg
> HFOV on slightly smaller film) I almost settled on this Schneider design b4 starting
> designing my custom designs.... it was that good... 10mm more of ER, and it would have
> been a slam dunk.
>
>
> http://www.schneideroptics.com/pdfs/photo/LoupeData.pdf
>
>
> If you shoot full frame 35mm, and use the RBT mounts from Jon Golden, they are 33mm wide,
> which will produce 43 deg HFOV with NO distortion, virtually no chromatic aberrations and
> excellent contrast. Compare this with 3dWorld MF viewer, at 75mm fl and 52mm wide film =
> 38 Deg HFOV. So it exceeds the HFOV of MF. Impressive, huh.
>
>
> If you have SHARP 35mm taking lenses, I would say these 6x loupes with 35mm
> film (considering how fine grain the chrome film is today) is in a dead heat with MF views
> in the 3dWorld viewer. Slightly less grain in the MF, a tad more sharpness of course,
> but less HFOV. Yep...but the the convenience and low cost of 35mm is tough to beat, and
> this is coming from a die-hard MF stereo guy :-) I never shot candids, till I got my
> first RBT 35mm stereo camera.... now i love it! There is some awesome RBT full frame
> 35mm stereo cameras with razor sharp modern optics that would make a perfect match. Many
> are early 2000 vintage.
>
> What 35mm stereo camera do you shoot with now?
>
>
> Anyway, don't take my word for it, stop down to B&H, they will take a pair of Schneiders
> out for ya, bring some stereo views and have a peek at how awesome a 35mm viewer can be!
>
>
> Bill
>

Subject: Re: Loreo loupe comparative review...
Date: 2010-09-02 10:14:45
From: Bill G

Lattie

> Hmmmm...the cost for a Schneider 6x pair would exceed a Combi lens set, but if it can
> compete with MF....Hmmmm. Can the lens housing be easily removed from the base for
> schleping into a viewer?

good questions....

1) The skirt on the 6x can be removed, this will enable space to join to mounts on a
common board. This will enable you to jury rig this into a viewer.... focus is from atop,
via a threaded barrel.

2) Cost - When I see a retail price of $220 for a loupe like this, I marvel such a low
volume product can sell this low. I am not suggesting its not a lot of money... Instead,
I find it remarkable they can recover their R&D, testing, markup, retail mark up and still
have a sell price this low. Of course I did not feel this way b4 I started designing and
building similar optics. Also, I have a wholesale account with Schneider direct in
Germany, I just checked the current price list... B&H sells these loupes retail less than
what I pay for them at my discount level. They get a larger discount and put a small mark
up on it, so I can't even help..

IMO, there is no comparison between this loupe and the Combi, but I think I paid $650 for
my Combi STL viewer, so there is some room to complete the viewer. Also, if these loupes
are discontinued, as everything in film is disappearing, well....yikes...

> I, (unsurprisingly ;-)) , prefer an underdog 35mm stereo camera! I'm hesitant to say what
> it is, because I'm still looking for cheap fixer-uppers on eBay. Let's just say that it's
> imported lens are only triplets, but still beat the pants off of most other classic stereo
> cameras I've seen! Knowledgeable stereographers have mistaken it's output for a 2.8 or
> Custom. But it's definitely not. ;-)

OK, my only reason for asking is.... the better the taking lenses (the
higher the contrast / resolution of the final film) the more value you will notice with
better viewing optics... its the mix of both, that creates the retinal nirvana you seek

>
> Just got another fixer-upper bargain of sorts - a French Hectron w/twinned FG-20s and 50mm
> Series E Nikon lens. I want to swap them out for some 35mm lens. Short of an RBT, I don't
> think the lens performance will be matched by other dedicated stereo cameras. ;-)
>
> Now...I wonder if the Nikon-Hectron teamed with the Schneiders would dissuade me from
> saving up for a TL-120?

I have a better solution for ya.... ya ready! (just a suggestion)

First you need to go try the 6x loupes to see how you react...remember, our visual systems
are different enough whereas you really do have to "see" to be sold. Also, see if B&H has
any high contrast film, shot with some Leica or M7 lenses. Use this as a comparison vs.
what you bring to the light box. Remember, the contrast recorded is half the battle here.

This is based on your desire tooooo go wide, or max HFOV when viewing.... The full frame
35mm I suggested would set you up with widest and highest quality viewer anyone owns... if
you want to go even wider on the viewing end, I have a MF suggestion for ya if your
interested....

Also, keep in mind, with these loupes, the taking fl of the lenses should be in the 30 -
40mm range to keep the views near ortho.... of course with 35mm format, the 35mm fl is
loaded with great lens options... so that works in your favor.

BTW, on the contact lenses, I forgot to mention. One of the biggest problems with
producing a very wide view optical stereo viewer is the 50% of the gen. population that
wears corrective eye-wear (vs. contacts) The reason is, eye glasses correct vision in
only a small field of vision, it varies based on the correction, frame type, etc. But on
avg, only about 25 - 30 deg HFOV. This is just barely acceptable with current stereo
viewers which all have very limited HFOV....but once you start exploring your IMAX viewers
(OK, its just true Cinema experience, not IMAX), corrective eye wear will NOT correct
vision throughout a field this wide. So you are entering uncharted waters :-)

In the real world, when you need to see something further to the right, you move your
head to the right, while the eyes stay centered in the area of the eye-wear which has the
correction... an optical stereo viewer is EXTREMELY unique in this regard. We must swivel
our eyes to look right, and therein lies one of the shortcomings of WA optical stereo
viewers for the gen. public. But this is why I suggested contacts offer such tremendous
value for stereo viewing (vs. eye-wear), as the contact lens tracks the movement of your
rotating eye, so you are fully corrected regardless of the angle your eye is viewing. So
IMO, contacts should be the top priority on your wish-list to gooooo wide.... not easy
feeding this addiction, huh....

Bill

>
> --- In MF3D-group@yahoogroups.com , Bill G
> wrote:
> >
> >
> > > Since we opened the loupe can 'o worms here....any opinions on the Schneider 10x
> > > aspherical loupe?
> >
> >
> > Yes, I have it.... it is 3 elements, no aspheres and a true 25mm fl...
> > the viewing circle is best suited for maybe 24x24mm film size.... and simply put, the view
> > is very poor, low contrast, hideous ER, and distortion that is beyond terrible. This is
> > what happens when you try to use only 3 elements to correct such a high magnification
> > lens. This loupe is really designed for close inspection, focusing on the very center
> > of the image area, maybe a viewing circle with a 15mm diameter. For stereo, it's a total
> > bust.
> >
> >
> > OTOH, the Schneider 6x aspherical loupe with 4 elements... and
> > considering it has an ashpere, the loupe is on par with a 5 element all-shperical loupe.
> > It has good ER, maybe 15 -17mm, with your lashes off the glass, you can see a full 24x33
> > frame. Contrast is superb, distortion is nill... as I mentioned previously, this ONE
> > loupe, a late entry into the loupe game, was the only loupe that benefited from the huge
> > increase in design capabilities that came along in the late 90's and early 2000's. The
> > only loupe I own that outperforms this loupe are my custom made loupes, and even then,
> > the gains are only in the area of ER, and slightly greater HFOV... (35mm fl, for 46 deg
> > HFOV on slightly smaller film) I almost settled on this Schneider design b4 starting
> > designing my custom designs.... it was that good... 10mm more of ER, and it would have
> > been a slam dunk.
> >
> >
> > http://www.schneideroptics.com/pdfs/photo/LoupeData.pdf
> >
> >
> > If you shoot full frame 35mm, and use the RBT mounts from Jon Golden, they are 33mm wide,
> > which will produce 43 deg HFOV with NO distortion, virtually no chromatic aberrations and
> > excellent contrast. Compare this with 3dWorld MF viewer, at 75mm fl and 52mm wide film =
> > 38 Deg HFOV. So it exceeds the HFOV of MF. Impressive, huh.
> >
> >
> > If you have SHARP 35mm taking lenses, I would say these 6x loupes with 35mm
> > film (considering how fine grain the chrome film is today) is in a dead heat with MF views
> > in the 3dWorld viewer. Slightly less grain in the MF, a tad more sharpness of course,
> > but less HFOV. Yep...but the the convenience and low cost of 35mm is tough to beat, and
> > this is coming from a die-hard MF stereo guy :-) I never shot candids, till I got my
> > first RBT 35mm stereo camera.... now i love it! There is some awesome RBT full frame
> > 35mm stereo cameras with razor sharp modern optics that would make a perfect match. Many
> > are early 2000 vintage.
> >
> > What 35mm stereo camera do you shoot with now?
> >
> >
> > Anyway, don't take my word for it, stop down to B&H, they will take a pair of Schneiders
> > out for ya, bring some stereo views and have a peek at how awesome a 35mm viewer can be!
> >
> >
> > Bill
> >
>
>

Subject: Re: Loreo loupe comparative review...
Date: 2010-09-02 10:25:06
From: Bill G

Lattie, its obvious this discussion is boring the list... and we are not in the domain of
the list, which is MF3d.

its best you email me direct if you need more info...

bglick@rconnects.com

Thanks
Bill

On 9/2/2010 6:58 AM, lattie_smart wrote:
>
>
> Hmmmm...the cost for a Schneider 6x pair would exceed a Combi lens set, but if it can
> compete with MF....Hmmmm. Can the lens housing be easily removed from the base for
> schleping into a viewer?
>
> I, (unsurprisingly ;-)) , prefer an underdog 35mm stereo camera! I'm hesitant to say what
> it is, because I'm still looking for cheap fixer-uppers on eBay. Let's just say that it's
> imported lens are only triplets, but still beat the pants off of most other classic stereo
> cameras I've seen! Knowledgeable stereographers have mistaken it's output for a 2.8 or
> Custom. But it's definitely not. ;-)
>
> Just got another fixer-upper bargain of sorts - a French Hectron w/twinned FG-20s and 50mm
> Series E Nikon lens. I want to swap them out for some 35mm lens. Short of an RBT, I don't
> think the lens performance will be matched by other dedicated stereo cameras. ;-)
>
> Now...I wonder if the Nikon-Hectron teamed with the Schneiders would dissuade me from
> saving up for a TL-120?
>
> --- In MF3D-group@yahoogroups.com , Bill G
> wrote:
> >
> >
> > > Since we opened the loupe can 'o worms here....any opinions on the Schneider 10x
> > > aspherical loupe?
> >
> >
> > Yes, I have it.... it is 3 elements, no aspheres and a true 25mm fl...
> > the viewing circle is best suited for maybe 24x24mm film size.... and simply put, the view
> > is very poor, low contrast, hideous ER, and distortion that is beyond terrible. This is
> > what happens when you try to use only 3 elements to correct such a high magnification
> > lens. This loupe is really designed for close inspection, focusing on the very center
> > of the image area, maybe a viewing circle with a 15mm diameter. For stereo, it's a total
> > bust.
> >
> >
> > OTOH, the Schneider 6x aspherical loupe with 4 elements... and
> > considering it has an ashpere, the loupe is on par with a 5 element all-shperical loupe.
> > It has good ER, maybe 15 -17mm, with your lashes off the glass, you can see a full 24x33
> > frame. Contrast is superb, distortion is nill... as I mentioned previously, this ONE
> > loupe, a late entry into the loupe game, was the only loupe that benefited from the huge
> > increase in design capabilities that came along in the late 90's and early 2000's. The
> > only loupe I own that outperforms this loupe are my custom made loupes, and even then,
> > the gains are only in the area of ER, and slightly greater HFOV... (35mm fl, for 46 deg
> > HFOV on slightly smaller film) I almost settled on this Schneider design b4 starting
> > designing my custom designs.... it was that good... 10mm more of ER, and it would have
> > been a slam dunk.
> >
> >
> > http://www.schneideroptics.com/pdfs/photo/LoupeData.pdf
> >
> >
> > If you shoot full frame 35mm, and use the RBT mounts from Jon Golden, they are 33mm wide,
> > which will produce 43 deg HFOV with NO distortion, virtually no chromatic aberrations and
> > excellent contrast. Compare this with 3dWorld MF viewer, at 75mm fl and 52mm wide film =
> > 38 Deg HFOV. So it exceeds the HFOV of MF. Impressive, huh.
> >
> >
> > If you have SHARP 35mm taking lenses, I would say these 6x loupes with 35mm
> > film (considering how fine grain the chrome film is today) is in a dead heat with MF views
> > in the 3dWorld viewer. Slightly less grain in the MF, a tad more sharpness of course,
> > but less HFOV. Yep...but the the convenience and low cost of 35mm is tough to beat, and
> > this is coming from a die-hard MF stereo guy :-) I never shot candids, till I got my
> > first RBT 35mm stereo camera.... now i love it! There is some awesome RBT full frame
> > 35mm stereo cameras with razor sharp modern optics that would make a perfect match. Many
> > are early 2000 vintage.
> >
> > What 35mm stereo camera do you shoot with now?
> >
> >
> > Anyway, don't take my word for it, stop down to B&H, they will take a pair of Schneiders
> > out for ya, bring some stereo views and have a peek at how awesome a 35mm viewer can be!
> >
> >
> > Bill
> >
>
>