---

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>I have a stereoview (took with my Sputnik) that looks fine in a 3D World
>hand held viewer but when put in the 3D-5T it gives a lot of eye strain.

Can you identify what is the cause of the eyestrain? Some type of
misalignment, but what kind? Looks to me that the optics are very similar
and I don't see how you can have a problem with only one view in this
viewer.

George

I took some time to investigate and I can say without a doubt that my
viewing experience is better with the hand viewer than with the 3D-5T with
EVERY stereoview I have. The faulty view is also a bit hard to view with the
hand viewer (I should remount that one...) but not as much as it is with the
3D-5T. There is definitely more optical distortion when I slightly move my
head back and forth to the left and right with my 3D-5T. I wonder if I could
replace those optics with better ones... Suggestion?

Any other opinion on that viewer?

Patrick

>From: "DrT (George Themelis)" <drt-3d@att.net>
>Reply-To: MF3D-group@yahoogroups.com
>To: <MF3D-group@yahoogroups.com>
>Subject: Re: [MF3D-group] 3D World coin-operated viewer
>Date: Thu, 1 Feb 2007 11:17:08 -0500
>
> >I have a stereoview (took with my Sputnik) that looks fine in a 3D World
> >hand held viewer but when put in the 3D-5T it gives a lot of eye strain.
>
>Can you identify what is the cause of the eyestrain? Some type of
>misalignment, but what kind? Looks to me that the optics are very similar
>and I don't see how you can have a problem with only one view in this
>viewer.
>
>George
>

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I have both a filter and a shade on my TL-120 and I have some very minor
vignetting at the extreme corners. I switched the order of the filters
by putting on the collapsible shade on before the UV filter and took a
roll with the shade collapsed. The frames show the exact same
vignetting so my conclusion is that stacking two items on the lens and
not the lens shade is the source of the vignetting, at least mine.

Dale Yingst

Patrick Dube wrote:

> I took some time to investigate and I can say without
> a doubt that my viewing experience is better with the
> hand viewer than with the 3D-5T ... I wonder if I could
> replace those optics with better ones... Suggestion?

I was under the impression that the lenses used in
the coin-op viewer were exactly the same as the
viewers used in the hand-held viewer.

Could the viewer lenses be un-parallel to the slide
drum (resulting in a tilted horizon)?

Could the plane of the slide drum be un-parallel
to the plane of the lenses (resulting in an image
focus-shift from left to right)?

Could the lenses be in the viewer-head backwards?
I haven't heart of any 3D-World viewers suffering
from this defect but it could account for the edge distortions.

I am very interested in your experience as I am
very close to dropping money on one of these
viewers for myself.

--
John Thurston
Juneau Alaska
http://stereo.thurstons.us

--- In MF3D-group@yahoogroups.com, John Thurston
wrote:

>

> Could the plane of the slide drum be un-parallel
> to the plane of the lenses (resulting in an image
> focus-shift from left to right)?

I have had an early model drum viewer for some time (pre-LED desktop
model). It suffers the same problem which I can report is
definitely a case of the drum not being parallel with the lens
plane. More a case of being out of alignment horizontally. It
appears to be caused by the fact that the drum is mounted on a much
too short axle. The axle is on the correct alignment but suffers a
little sagging away from the true horizontal. Even though the
freeplay is minimal, it is just enough to through it off alignment
and just enough to be uncomfortable as you have experienced. I
believe they chose this short axle so as not to interfere with the
position of the bulky light globes used prior to the advent of the
LED panels. Now that they have the LEDs, there would be more room
for a longer axle which would solve the problem.

When I contacted 3D World about this, they said "No-one else has
complained" so I can only urge you to let them know that it is a
problem and needs to be addressed. I have found that 3D World takes
little notice of just one complaint.

If I may digress a little, mounts are an other issue that I have
contacted them about. Like many, I would love to see a landscape
and a portrait mount as well as the standard square. They again
told me that no-one else has requested these.

Maybe if more of us voiced our opinions directly to them, as well as
on this forum, they may address these matters.

Getting back to the problem of the mis-alignment, the only way I can
see to adjust this is to remove the whole central assembly inside
the viewer and then remount it with a couple of very thin spacer
washers in the top mounting screws. This would effectively create a
situation where the drum would then "sag" back to being level again.

To Patrick, if you do contact 3D World about this, please let me
know how you go or what response you get.

regards,

Harry Calderbank
hcalderbank@bigpond.com

I don't think my upright viewer is any different than my China World
hand viewer, but I did make some observations. When looking through the
hand viewer the viewer remains planted to your face even though you move
your head. In the upright viewer, even with height adjustment, you
probably do some amount of stooping or stretching to look, while keeping
your head at the best angle for viewing. So with any head or body
movement, the upright viewer does appear to give more off center viewing
distortions.

I just got my viewer (ordered in 8/06) and even though the manual shows
the LED panel, it has the fluorescent bulb. Having the LED in my
mounter, I find the fluorescent light source in the upright viewer to
be both brighter and whiter. That being said, different slides of mine
look better under different lights. Richer colors look better with the
fluorescent strong lighting while lighter, especially slightly over
exposed, slides are better with the LEDs. I think my best compromise is
to slip another layer of diffuser in front of the florescent bulb just
to cut the light back a tad. I'll try that this weekend.

Even though I said I now like my modified China World mounter, I did
discover a problem with a couple slides in my upright viewer. The
raised glass surface on the mounter has a prismatic effect around the
edges of each aperture that creates a grayed out perimeter that is
harder to see. I ended up mounting a couple slides with borders
extending into the image that I didn't notice until viewed in the
upright viewer.

Dale Yingst

Harry Calderbank wrote:

> . . . mounts are an other issue that I have
> contacted them about. Like many, I would
> love to see a landscape and a portrait mount
> as well as the standard square. They again
> told me that no-one else has requested these.

With those big 52mm square apertures and the
stiff plastic frames, I'm really curious if
aluminum masks (inserted during mounting) are
a viable way to get different apertures. We
could have rectangular, round, elliptical, and
even trapezoidal for a tilted-plane window.

Having never seen one of the older 35mm masks,
I don't know how thick or thin the aluminum has
to be. It has to be opaque but must be thin
enough to fit cleanly in the mount.

How would one go about manufacturing these?
--
John Thurston
Juneau Alaska
http://stereo.thurstons.us

--- In MF3D-group@yahoogroups.com, John Thurston
wrote:

>
> With those big 52mm square apertures and the
> stiff plastic frames, I'm really curious if
> aluminum masks (inserted during mounting) are
> a viable way to get different apertures.

Steven Sawyer once sent me a slide mounted in one of 3D World's old
54 x 54mm mounts but he had used a couple of Gepe aluminium masks.
It worked really well and the aluminium masks fitted in quite
easily. It would be better to have a one piece unit with two
apertures but the concept is good. I know I will be looking into
this and any other possibilities to get the desired apertures. 3D
World are proving quite stubborn on the matter and I have had no
luck with the cardboard RMM mounts as the last batch of them had a
bad curve on one side of one aperture. As yet, no replacement for
the defective mounts has arrived.

regards,

Harry Calderbank
hcalderbank@bigpond.com