I just read Mike Davis' very informative posting regarding the
specifications that the new viewer should have:

----- Original Message -----
From: "Michael K. Davis" <zilch0@primenet.com>

> Ideally, viewer lenses should remain separated at a distance equal to
> window separation + MAOFD + a little bit more (0.5mm?) to accommodate
> OFD's that exceed MAOFD.

Very nicely stated :)

> 3DWorld's 75mm lenses in combination with
> mounts having a 62mm window separation require a minimum lens
> separation of 62mm + (75mm/30) + 0.5mm = 65mm. (The 3DWorld STL
> viewer has a fixed lens separation of 64.5mm, by the way, omitting
> the 0.5mm safety margin.) If the lenses are brought closer together
> than window separation + MAOFD + 0.5mm over chips that remain
> stationary relative to each other, the user's eyes must diverge to
> fuse the Infinity homologs of views that have an OFD equal to (or
> greater than) MAOFD + 0.5mm. A little bit of divergence is tolerable
> among those of us who are rubber-eyed, but for others it will be
> fatiguing.

Yes, I am in full agreement.

> Moving the lenses in the opposite direction, farther apart than
> window separation + MAOFD + 0.5mm, is much less of a problem, because
> that only requires users to apply more convergence (a much easier
> task for most people) and it would allow those with IPD's greater
> than 65mm (like me) to enjoy the lack of distortion had when the eyes
> are on-axis. If 3DWorld can incorporate an adjustable interocular
> without increasing the overall cost by more than say 15% and without
> compromising our desire for a focusing viewer (which I suspect would
> be very hard to do), then I'd say it's OK, but they should not allow
> a separation any less than about 63mm, in my opinion (a shift of
> -2.0mm from the window separation + MAOFD + 0.5mm position).

OK, and here is where 3D World got it wrong.

The minimum viewer lens separation is 61mm, which is worthless.

The maximum appears to be closer to 66mm (I repeated the measurements).
This maximum separation might be the position that most people will use
the viewer, making the adjustment useless.

Personally, I would have been happier with a rage of 64 to 68mm. And then
I would have used the viewer at the widest setting, which I find more
comfortable.

Regarding focusing, I measured the focusing travel and it is an amazing
18mm. Unfortunately, as I said, it is in only one direction, and for my
eyes, when the lenses are pushed the furthest from the slide, I still
cannot focus infinity well.

George Themelis

I finally was able to print a scanned MF transparency onto Pictorico inkjet transparency paper using an Epson 4880 which claims 2880 x 1440 resolution.  I wanted to report that the results were pretty terrible.  To the naked eye things look OK but in the 3D world viewer, they look dismal.  The raster lines are very visible and the colors are muted compared to the original.

Well, it was worth a shot.

I guess a Polaroid ProPalette 8000 with MF or 4x5 back is the only way to go?

Aaron

--- In MF3D-group@yahoogroups.com, Aaron Muderick wrote:

>
> I finally was able to print a scanned MF transparency onto Pictorico
> inkjet transparency paper using an Epson 4880 which claims 2880 x 1440
> resolution. I wanted to report that the results were pretty terrible.

I actually had decent results (for what I wanted) using Inkworks ultra-
white photo glossy inkjet film to make MF pairs from digital files.
Transparency film looked relatively awful, but these
weren't "terrible". Good color and contrast, pretty poor resolution
(as I expected) but not with obvious scan lines.

I showed some at NSA2006 (or was it 2007,,, duh). Cost per MF pair was
about 10 cents! My goal was to be able to make "proofs" in near real-
time in order to show competition kayakers how they were doing, in 3D.
Sure there is no comparison with real MF's, or even film recorder
MF's. But with a bright light source (like a sunlit wall) and a 3D
World viewer, not bad. Several people signed up for the real deal (MF
slide output from slides.com), and some bought a viewer and the cheapy
prints (a.k.a. MF slides!) on the spot.

It was an interesting little project, and far cheaper than buying and
maintaining a fancy but out-of-date film recorder (I choose to let
someone else do that .... I'd rather be out shooting ;-).

FWIW,

John

DrT (George Themelis) wrote:

> OK, and here is where 3D World got it wrong.
>
> The minimum viewer lens separation is 61mm, which is

worthless.

I agree. Any separation less than the window separation of
the slide mount is useless. However in a folio I recently
had I measured infinity spacing of the slides and found the
smallest to be 62.2 mm. An adjustment close to 62mm would
be needed to get a parallel view to infinity with that
slide. I would say that an interocular range starting at 62
mm could be usable.

>
> The maximum appears to be closer to 66mm (I repeated the

measurements).

> This maximum separation might be the position that most

people will use

> the viewer, making the adjustment useless.

I would like to see the interocular fixed at 65 mm and any
adjustment useless. But since the common practice of
mounting slides "To the Window" has the infinity spacing
somewhat variable, a variable IO is called for.

I found the widest infinity spacing in this resent folio to
be 67 mm. So for this folio, someone wanting to get as many
depth cues as possible in alignment would want a variable IO
from 62.2mm to 67mm. This range could easily be different
in another folio so maybe a range of 62 mm to 68 mm or more
would be more useful.
(However, I could live with the 61 mm to 66 mm range)

> Regarding focusing, I measured the focusing travel and it

is an amazing

> 18mm.

I measured the focusing travel in my Saturn to be 23mm. I
use it just a touch in from all the way out.

>Unfortunately, as I said, it is in only one direction, and

for my

> eyes, when the lenses are pushed the furthest from the

slide, I still

> cannot focus infinity well.
>

I think 3D World should have an old guy as a Test Engineer.
%^)

Chuck Holzner

Hi,

George sent me one of the new 3DWorld illuminated viewers and it
arrived today. (Thank you George!)

LENSES:

Without question, this new 3DWorld illuminated viewer has the very
same 75mm achromatic doublets we've been enjoying in the 3DWorld STL
viewer, but they're mounted in nicely machined metal barrels
(anodized aluminum?), that extend as much as 25mm beyond the rear of
the viewer when focusing. Just as with the STL viewer, these lenses
are sharp right into the corners of the frame, with no apparent
chromatic aberration and just a hint of pincushion
distortion. Focused at infinity, the math says these 75mm lenses
will provide a magnification of 3.4x. But here's the best
part: The lenses can be easily removed for cleaning by just
unscrewing the front bezel of each lens barrel. I really like this feature.


INTEROCULAR ADJUSTMENT:

Summary:
Confirming George's measurements, the Interocular adjustment range of
this new viewer (61mm to 66mm) is set too low - even for people with
IPDs (inter-pupillary distances) small enough to match the lesser
values - because they will suffer divergence when trying to fuse
Infinity homologs that are farther apart than the lens separation.

Detail:
The minimum IPD that can be supported by any Brewster-style viewer is
equal to the Window Separation of the mounts being used + the largest
OFD anticipated. If the stereographer is diligent to limit the
recorded OFDs to MAOFD (where MAOFD = Viewer FL / 30), then any user
having an IPD equal to Window Separation + MAOFD will be able to fuse
Infinity homologs without having to diverge the eyes.

MAOFD for this viewer is 75/30 = 2.5mm. Adding this MAOFD to the
mount's Window Separation of 62.0mm, we can calculate that there was
no need to provide lens separations less than 64.5mm. 64.0mm would
be OK as a minimum when looking at views having OFDs a little less
than MAOFD, which is pretty common, but the eyes can easily converge
to fuse Infinity homologs that reside at a separation less than IPD,
just as it's easy for the eyes to converge Near homologs that reside
at or near the Window Separation. I nevertheless agree with
George's recommendation that 3DWorld shift their 5mm adjustment
range from 61-to-66mm up to 64-to-69mm.

The viewer actually works pretty well with my 70mm IPD when the
interocular adjustment is set to the current maximum separation of
66mm. I'm having to position my eyes two millimeters off-axis with
each lens - to the outside of center, but I'm still able to see what
appears to be an undistorted image, at least when looking at
landscape views. The straight lines of buildings and such would be
more revealing for those of us who can't get our eyes over the lens
axes. The maximum separation of 66mm is 1.5 mm greater than that of
the 3DWorld STL viewer's fixed separation of 64.5mm, so if your IPD
is wider than 64.5mm and the STL works OK for you, then this new
viewer will, too - in terms of lens separation at least (ignoring focus).

In short, less than half of the interocular adjustment range is
useful, from about 63.5mm (for views that have OFDs which are only
about 60% of MAOFD) to the maximum 66mm (which offers only 1/2 a
millimeter more than the optimum separation for a fixed-interocular
viewer equipped with 75mm lenses and masks using a 62mm window
separation: 65.5mm (Window separation + MAOFD + 0.5mm, where MAOFD =
Viewer FL / 30).

Alan Lewis got this right with his SaturnSlide viewer. In fact, I
attribute my understanding and appreciation of this requirement to
Alan's lead test engineer and retailer, Paul Talbot - I'm just
echoing Paul's terrific tutelage.

One last thing: The lenses can be moved left and right independent
of each other - not a good thing - so be careful when selecting an
interocular adjustment other than 66mm.


FOCUS ADJUSTMENT:

Summary:
I agree with George's observation that it's impossible to achieve
Infinity focus with this adjustable focus viewer. I am only just
barely able to enjoy a sharp view when the lenses are focused as far
away from the film as possible. I can't believe 3DWorld got this wrong, too.

Detail:
The control levers are linked - as they should be to avoid dissimilar
magnifications - you can't focus the lenses independently. They're
not as klunky as you might imagine - but they just don't offer the
precise control that would have come with round knobs. In my case,
it doesn't matter, because I'm having to run the focus all the way out.

I've noticed that after using the viewer for a while the lenses
creeps back toward the film a little bit, which is all it takes to
ruin the focus - I then have to twist the levers back up to where
they were - easy for me, in that I need the lenses all the way out,
but I think this could be a pain for someone who's trying to maintain
a focus position somewhere short of that. The focus tension is not
adjustable and it's set about where you'd want it for a design that
lacks round knobs - any tighter and it would be really difficult to
fine tune, but if you apply any pressure to the lens barrels at all
while looking at views, you'll soon find yourself having to run the
lenses back out to where you prefer them.

I'd like to see a redesign that accommodates Infinity focus (plus a
couple of millimeters), knobs instead of levers, and either more
tension in the focus travel -or- a set screw. Alan Lewis also got
this right with his SaturnSlide viewer - as simple as the focusing
was - a box sliding within a larger box - it suffered none of the
focusing problems inherent with 3DWorld's new viewer.


ILLUMINATION:

Summary:
I am blown away with how uniform the illumination is with this new
3DWorld viewer and I'm really pleased with the color of the
light. These attributes are quite remarkable, but I'd have say they
come with a luminance level that is only just adequate.

Detail:
The viewer does not provide a barrel jack for plugging in an external
power supply, so unless you modify it, you're stuck with using three
AA batteries. Starting out with a fresh set of Duracell Alkalines,
the light level in the viewer is less than ideal, in my
opinion. It's certainly tolerable, but I'm wondering how I will feel
about it once the batteries get down to about 70 or 50% of
capacity. Alkaline batteries have a very linear discharge curve,
losing voltage quite uniformly over there useful life, but it's
sloped, nevertheless, not flat out to a shoulder that drops off rapidly.

Rechargeable batteries, either NiMH or NiCd AA's, typically start out
with less voltage than Alkalines, so I'm pretty sure the viewer would
be even less bright using rechargeables. Non-rechargeable Lithium
AA's (like the Energizer Lithium e2) might be the best way to go, as
they offer pretty much the same or a higher starting voltage than
Alkalines but outperform Alkalines in terms of life span when not in
use AND when under loads exceeding about 300 milliamps - the higher
the load, the longer Lithiums last compared to Alkalines. I suspect
the LEDs in the 3DWorld viewer are pulling at least 300 milliamps,
but they might be more efficient than that. In any case, even if the
Lithiums don't last any longer than Alkalines, their voltage will
remain relatively constant (the viewer will remain nearly as bright
as when the batteries were new) all the way out to a cliff that
suddenly drops at the end of the batteries' useful life. I'll leave
it to the reader to decide if any of this holds true with the viewer
and whether or not the added expense of non-rechargeable Lithium AA's
is worthwhile.


DIFFUSER:

Summary:
The diffuser does it's job well, but it's sitting too close behind
the film plane. When the viewer is focused at the film plane, dust
on the surface of the viewer can still be seen as bokeh blobs.

Detail:
The diffuser is about 12 to 13 mm behind the film plane, but this is
close enough for dust to be a problem. I haven't taken the viewer
apart yet, but I'm encouraged by George's discovery that removing a
single screw in the bottom of the battery compartment allows one to
access the diffuser. Short of taking the time to do that, I was
pretty successful at cleaning the diffuser just by using a can of
compressed air equipped with a thin tube that can be inserted into
the slot where you load your mounted views. There remains, however,
one speck of something that I'll have to remove by taking the viewer
apart. Ultimately, blowing compressed air into the viewer doesn't
accomplish much because there's the viewer has no vents - there's
nowhere for anything to go except back through the loading slot.


LOADING SLOT:

Summary:
It works very well with 3DWorld plastic mounts, but it's too deep for
The Quellen Company's Q-VU or Rocky Mountain Memories-style card mounts.

Detail:
This slot is more narrow than the one in the 3DWorld STL viewer. The
3DWorld plastic mounts are snug going in and out - with no wobble
whatsoever once seated in the slot. I'd almost say it's a tight fit,
but that's not a bad thing, necessarily. When I first made this
observation, I thought that this would be better for the Q-VU /
RMM-style mounts because those tended to flop to and fro in the wider
slot of 3DWorld's STL viewer. Unfortunately, where the STL viewer's
larger diffuser makes it at least possible to use the RMM mounts
without modification, the compact light source of this illuminated
3DWorld viewer simply will not accommodate a mount that positions the
film chips lower than their plastic mounts. The mounts drop in just
fine, but they sit so deep in the slot that about the bottom 10mm of
a 50x50mm window is poorly illuminated.

A while back, I constructed an adapter for using my 80x132mm RMM
mounts in the 3DWorld STL viewer, following John Thurston's
recommendations at this page of his web
site: http://stereo.thurstons.us/mountcarrier.htm (Thanks
John!) Where it's just a nicety with the STL viewer, John's adapter
is a necessity for using RMM mounts with the new illuminated viewer -
it works really well - elevating my views to center them behind the
lens where they belong, with no more shadows getting cast across the
bottom of the frame.


MOMENTARY CONTACT SWITCH:

I really like both the location and function of the momentary contact
switch. It doesn't require a lot of pressure to keep depressed and
it's positioned so perfectly for the right index finger that you
immediately acclimate to using it. And it makes sense to use a
momentary contact switch with LED's as they don't put an startup
drain on the batteries the way florescent or cold cathode sources
do. This is a valuable, battery-saving design.


INTERNAL REFLECTIONS:

I was again dismayed when I discovered that the interior is
constructed of black plastic with a high-gloss
finish. Arrrgh! Oddly, the exterior walls, to the left of the left
eye and to the right of the right eye, are pitch black voids - the
light simply doesn't get to those surfaces, but both sides of the
central septum as well as the top and bottom surfaces of both tunnels
are in need of a good flocking. These surfaces are simply in
geometry, so it shouldn't be hard to cut, fit and apply a
self-adhesive flocking material where needed.


THE VIEW:

Somehow, despite its less than ideal brightness, its dust-showing
diffuser, the glare of its internal surfaces, the awkward focusing
levers, the lack of a focus lock, the loading slot that's just a
little too tight, the lack of an external power jack, and despite my
eyes being only just barely compatible with the ridiculous
misplacement of both the focus range and the interocular adjustment,
I have to say I'm impressed with what I see in the
viewer. Truly! At least with a clean diffuser and a fresh set of
batteries, using it indoors, with either the 3DWorld plastic mounts
or with RMM mounts fitted to John Thurston's adapter, this thing
rocks! I genuinely like what I see - especially the color and
uniformity of the light, in combination with those great lenses - the
view is really nice.

CONCLUSION:

There's a lot to like about this viewer, just as it is. It's
cosmetically attractive, instantly comfortable in the hands, compact
(perhaps to a fault), but I'd much rather have one of these than the
3DWorld STL viewer. I think it will be well-received by the majority
of users, but I'd very much like to see 3DWorld correct some of the
problems that are holding it back from being a really great value
instead of just a good value. It's the only illuminated MF viewer
available, so for that reason alone we should be appreciative, but
let's encourage 3DWorld to make some improvements the way they did
their TL-120 camera.

Mike Davis

Thanks Mike for the comprehensive review.

Here is an update from my side: While trying to convince 3D World to
change the ranges of focusing and interocular, I was asked this question:

1. "You said that you have perfect distant vision. How is your near
vision? Are you presbyopic? Do you need/use reading glasses?"

Yes, of course, I am presbyopic, like just about anyone over 40 years old
with good distant vision. I need +1 to read normally, and maybe +2 reading
glasses when I read at bed (low light).

I can see them smiling and thinking "so, you do not have perfect vision
after all". I tried to explain that the most comfortable focusing of a
viewer (especially if you are looking at something that contains infinity)
is "at infinity". The viewer is not a book. I don't think they get this.
So, I might need to put on my reading glasses, to get a good focusing
range with their viewers.

2. Regarding the interocular adjustment, they said "most people's eyes
spacing is from 62 to 66mm which is why we set the same spacing on the
viewer"

It is amazing to me that after all these years of making stereo viewers
(not only MF viewers, they also make 35mm stereo viewers for a long time),
they still think that a viewer is focused like reading a book and the
spacing of the lenses should match the spacing of the eyes.

In the meanwhile, I started doubting my own vision. The other day I was
in a show where a fellow 3D photographer had set a stereo viewer for
public display. I tried to view through the viewer and I was seeing double
images. I *had to* increase the interocular in order to fuse infinity.
"Why do I have do this and he doesn't?" I know my eyes are a bit
exophoric, i.e, they tend to converge when relaxed. I have trouble fusing
infinity in some viewers/images (like VM) where others don't. I always
tend to set the interocular a bit wider than most people. Also, his focus
did not match mine. My wife, daughter and son ALWAYS focus the stereo
viewer closer than I do. I know my son is myopic and does not wear his
glasses. My daughter has contacts and my wife is (I thought) OK.

So maybe I have the problem. That's why I wanted to get the viewer out to
more people for testing.

To be continued in the next message...

George Themelis

> CONCLUSION:
>
> There's a lot to like about this viewer, just as it is. It's
> cosmetically attractive, instantly comfortable in the hands, compact
> (perhaps to a fault), but I'd much rather have one of these than the
> 3DWorld STL viewer. I think it will be well-received by the majority
> of users, but I'd very much like to see 3DWorld correct some of the
> problems that are holding it back from being a really great value
> instead of just a good value. It's the only illuminated MF viewer
> available, so for that reason alone we should be appreciative, but
> let's encourage 3DWorld to make some improvements the way they did
> their TL-120 camera.
>
> Mike Davis

"Michael Davis" wrote:

>
>
> In short, less than half of the interocular adjustment

range is

> useful, from about 63.5mm (for views that have OFDs which

are only

> about 60% of MAOFD) to the maximum 66mm (which offers only

1/2 a

> millimeter more than the optimum separation for a

fixed-interocular

> viewer equipped with 75mm lenses and masks using a 62mm

window

> separation: 65.5mm (Window separation + MAOFD + 0.5mm,

where MAOFD =

> Viewer FL / 30).
>

Mike,
Check you math on the above, please.

62mm + 2.5mm = 64.5mm + .5mm extra (for tolerances) = 65mm.

> Alan Lewis got this right with his SaturnSlide viewer.

62mm + 3mm (1.2 X 75mm/30) + .5mm = 65.5mm

The Alan Lewis Saturn viewer will easily handle an OFD of
3mm and still have .5mm extra as its IO is 65.5mm. "Alan
Lewis got it right with his SaturnSlide viewer" so why is
an IO adjustable to 69mm needed?
(6.5mm OFD or you want to "converge on infinity"?)

Changing the IO adjustment range will likely mean a new
mold. $$$

> FOCUS ADJUSTMENT:
>
> Summary:
> I agree with George's observation that it's impossible to

achieve

> Infinity focus with this adjustable focus viewer. I am

only just

> barely able to enjoy a sharp view when the lenses are

focused as far

> away from the film as possible. I can't believe 3DWorld

got this wrong, too.

There had been some mention as to the lenses maybe being
screwed out of the housing some to make for a longer focus
distance. Do you have any comment on that?

Thanks,

Chuck Holzner

Hey Chuck,

At 12:10 AM 9/9/2008, you wrote:

>"Michael Davis" wrote:
> >
> >
> > In short, less than half of the interocular adjustment
>range is
> > useful, from about 63.5mm (for views that have OFDs which
>are only
> > about 60% of MAOFD) to the maximum 66mm (which offers only
>1/2 a
> > millimeter more than the optimum separation for a
>fixed-interocular
> > viewer equipped with 75mm lenses and masks using a 62mm
>window
> > separation: 65.5mm (Window separation + MAOFD + 0.5mm,
>where MAOFD =
> > Viewer FL / 30).
> >
>
>Mike,
>Check you math on the above, please.
>
>62mm + 2.5mm = 64.5mm + .5mm extra (for tolerances) = 65mm.

I think you must have missed my qualification regarding
63.5mm: "(for views that have OFDs which
are only about 60% of MAOFD)". In other words, a 63.5mm lens
separation would handle views with an OFD that's only 1.5mm (60% of
MAOFD) for a 62mm window separation, but not views with OFDs greater
than 63.5mm - not without causing divergence for those with IPDs of
63.5mm or less. If it was someone's preference to always shoot at
60% of MAOFD, following the "less is more" thinking, 63.5mm would
handle that just fine without requiring users to diverge their eyes
to fuse Infinity homologs.

But for a viewer that can handle any OFD up to MAOFD, then yes,
64.5mm would be the smallest desirable lens separation for a 62.0 mm
window separation, and an extra 0.5mm on top of that would
accommodate OFDs up to 120% of MAOFD - a la SaturnSlide.

> > Alan Lewis got this right with his SaturnSlide viewer.
>
>62mm + 3mm (1.2 X 75mm/30) + .5mm = 65.5mm
>
>The Alan Lewis Saturn viewer will easily handle an OFD of
>3mm and still have .5mm extra as its IO is 65.5mm. "Alan
>Lewis got it right with his SaturnSlide viewer" so why is
>an IO adjustable to 69mm needed?
>(6.5mm OFD or you want to "converge on infinity"?)

Either of the above or any combination of the two? :-)

Actually, I was only considering the "converge on Infinity" half of
your question.

If you're making an argument for a fixed lens separation, I hear you
loud and clear, 65mm would be ideal for a 62mm window separation with
75mm FL lenses, but these 32mm diameter lenses don't have as large a
clear aperture as the 46mm SaturnSlide lenses, and given that
limitation, I'd rather have a viewer that opens the audience to a
larger population of IPDs, some of which will have to converge their
eyes to fuse Infinity - but this is exactly what SaturnSlide users
with 65mm IPDs or greater do every time they look at a view having an
OFD less than 120% of MAOFD - which is the case for the majority of
views. Converging to fuse Infinity homologs isn't a
problem. Picking up a viewer that simply doesn't fit your IPD is a problem.

>Changing the IO adjustment range will likely mean a new
>mold. $$$

That's why I gasped when George first reported these
problems. 3DWorld is so capable when it comes to producing stuff,
yet equally incapable of doing R&D (emphasis on the "R"). They
exhibit a lot of ingenuity in solving mechanical and other design
problems, not to mention all it takes to actually bring these
products to market, but they exhibit almost no ability to seek out
and employ information that's readily available and in some cases, as
old as the hills. Thus the ludicrous design flaws. Their products
are doomed to always be a mix of components that are sophisticated
alongside components that are primitive - a solar-powered vehicle
with square wheels. They really don't know that the wheels should be
round - everyone else does, but they don't.

> > FOCUS ADJUSTMENT:
> >
> > Summary:
> > I agree with George's observation that it's impossible to
>achieve
> > Infinity focus with this adjustable focus viewer. I am
>only just
> > barely able to enjoy a sharp view when the lenses are
>focused as far
> > away from the film as possible. I can't believe 3DWorld
>got this wrong, too.
>
>There had been some mention as to the lenses maybe being
>screwed out of the housing some to make for a longer focus
>distance. Do you have any comment on that?

I think all you'd need is some spacer rings (I'll leave it to others
to figure out how to make these), that would force the glass to sit
farther out in the barrel by just one millimeter. I think there's
enough thread where the bezels meet the barrels to still get a few
turns with the spacers in place - enough to secure the lenses.

Mike Davis

"Michael Davis" wrote:

> I think all you'd need is some spacer rings (I'll leave it

to others

> to figure out how to make these), that would force the

glass to sit

> farther out in the barrel by just one millimeter. I think

there's

> enough thread where the bezels meet the barrels to still

get a few

> turns with the spacers in place - enough to secure the

lenses.

>

So are you saying that 1mm more lens to film spacing will
focus the viewer to infinity focus when it is focused all
the way out? I know I would need more than that to focus it
for my eyes.

Of course having infinity focus in the middle of the focus
range would be ideal. (If the range was enough.)

Chuck Holzner

> So are you saying that 1mm more lens to film spacing will
> focus the viewer to infinity focus when it is focused all
> the way out?

Mike described this very well. A simple plastic spacer will move the
lenses forward and there is room for this. I think there is room for
3-4mm not just 1mm. And this will do it for me. I do not have a viewer
to check it out but I will when I get new stock. I suspect that the
viewer will work for a lot of people as-is, but I need the few
millimeters.

> Of course having infinity focus in the middle of the focus
> range would be ideal. (If the range was enough.)

Just put on a +2 pair of reading glasses :) (just kidding - but it works)

George

Hi Mike,

Thank you for this most thorough evaluation of the new 3D World
viewer. It's hard to believe that 3D World still manages to make
errors that one would expect of someone who has no experience
whatsoever in stereo design. The problematic characteristics
mentioned would have been so easy to get right.

In regards, the light panel, how does the illumination compare to that
on the 3D World mounting jig and do you think it would be possible to
rig an outlet for an external AC adapter ?

Francois

"DrT (George Themelis) wrote:

> Just put on a +2 pair of reading glasses :) (just

kidding - but it works)

I can not use the Cheap plastic (old china) viewer because
the focus was way too far off and there was not enough "eye
relief" to use it with glasses. The new viewer has the same
lenses but now the lenses have enough eye relief to use them
with glasses?. Did you actually try?

Chuck Holzner

> The new viewer has the same
> lenses but now the lenses have enough eye relief to use them
> with glasses?. Did you actually try?

Yes, I did try to use the viewer with reading glasses... just for the fun
of it, and I was only paying attention to the focusing, not the eye
relief.

I understand that simple achromatic lenses have zero eye relief. It is
usually an issue of the design of the lens holder, if it allows you to
bring the glasses as close to the lenses as possible or not. If the
simple viewer did not work for you and your glasses, the new viewer might
not work either, but I have to measure how close the glasses can come to
the lenses in either viewer, to tell if there is any difference.

George

--- In MF3D-group@yahoogroups.com, "DrT \(George Themelis\)" 3d@...> wrote:
I suspect that the viewer will work for a lot of people as-is, but I
need the few millimeters.

If you need a few millimeters, I will need a centimeter....... (err,
give yourself another 10 - 15 years).

John

Hi Francois,

I'm glad you enjoyed the review.

At 10:27 AM 9/9/2008, you wrote:

>In regards, the light panel, how does the illumination compare to that
>on the 3D World mounting jig and do you think it would be possible to
>rig an outlet for an external AC adapter ?

I've never used, nor even seen one of the 3DWorld mounting jigs, but
I trust Bill Glickman's ability to assess hardware and he has said it
has really good illumination - and that it makes a pretty nice little
viewer. He also said that it's not hard to remove it from stand that
normally supports it on a table top. I also know that he's very
keen on viewers having bright illumination, so comparing his comments
to my observations with the new, battery-operated viewer, I'd say
it's very likely that the 3DWorld Mounting Jig is brighter.

I passed the new 3DWorld viewer around at work today to five of my
coworkers and none of them complained about any lack of
brightness. I honestly don't think it's a serious problem, by any
means, at least not with fresh batteries. It's just not as bright
as I would prefer.

At least three or four of my coworker test subjects have handled
every viewer that I've ever had in my possession at one time or
another. Three out of today's five people wear eyeglasses because
they are nearsighted. Taking off their glasses, they found they
could adjust the focus to suit their eyes, just by coming about
half-way in. I don't think any of this group of three are severely
myopic; they're just mildly so.

The other two out of five found that the only way they could focus
their eyes correctly was to run the viewer lenses all the way out -
just as I do. Neither one of them wear eyeglasses or contacts - and
neither do I - except for reading. Add my wife and you have a total
of four people, including myself, who do not require correction to
focus our eyes at Infinity, yet all four of us have to run the viewer
lenses all the way out, but we can all use the viewer. I think
we're all straining a bit to make it work, however - that's why I
think just another millimeter of travel would make it perfect for me,
but why stop there? The viewer should have been given at least
another 5 millimeters of travel, if not more. I've not seen anyone
use the lower end of the focus range. It's useless for all but the
severely myopic, in my opinion, but my testing is far from comprehensive.

Back to your questions: I think it would be very easy to install a
power jack. The wiring is readily accessible inside and there's are
several places where you could mount the jack. I'd be curious to see
if the LED assembly could handle an extra 1/2 a volt without
suffering any damage. Three AA's put out 4.5 Volts, so the safe bet
would be to buy a 4.5 Volt DC power adapter with a rating of at least
500 milliamps. (I'm just guessing at the load, but it never hurts to
use a power supply that's capable of more than what the device demands.)

I just went searching for a 4.5 Volt DC power adapter and the first
one I found happens to be rated at 500 mA:

http://www.shoplet.com/Dc-Adaptor-4.5v_285659/office_supplies.html

If I was a betting man, I'd say John Thurston will be the first
person to experiment with this. :-) I'm looking forward to reading
his review of the viewer George sent him. I suspect he will dig into
the internals far better than I have.

Mike Davis

Hey Chuck,

I just put on a pair of reading glasses and tested the eye relief to
simulate your situation as best I can. First, let me say that I can
literally touch glass-to-glass. The bezels that secure the achromats
in the barrels are so thin, you can easily touch your naked eyes to
the lenses. That's certainly promising for eyeglass wearers, but when
my reading glasses are as tight against my face as is still
comfortable and they are literally touching the viewer lenses,
glass-to-glass, I'm still not close enough to see the corners of the
stereo view. They are just barely out of sight - I have to wiggle a
bit to see them. But this could very easily be different from one
person to the next and one eyeglass frame to the next. I can easily
insert my index finger atop a closed eyelid without touching the
backside of my reading glasses, so I suspect that a frame design that
places the eyeglass lens closer to the eye itself might permit one to
get close enough to see the entire stereo view.

I wish I could have given you a more positive analysis, but this much
is certainly true - the lenses aren't set back behind temple guards
the way they are in the 3DWorld STL viewer - they're right up front.

Mike Davis

Michael Davis wrote:

> If I was a betting man, I'd say John Thurston will be the
> first person to experiment with this. :-) I'm looking
> forward to reading his review of the viewer George sent
> him. I suspect he will dig into the internals far better
> than I have.

I have my light and power meters standing by. As soon as that
viewer arrives, all be all over and in it. Unfortunately, the
post takes a little longer to get to us here in Alaska. If it
gets on a plane in Seattle, I should see it tomorrow or
Thursday. If the box went on a barge, I may not see it for
weeks :(

I've also been thinking about color temperature. Because
white LEDs actually contain three emitters, they can vary in
color quite a bit as you vary voltage. Most turn distinctly
blue as they are driven with more than their designed voltage.
________________________________________
John Thurston
Juneau, Alaska
http://stereo.thurstons.us