Re: [photo-3d] 15/70 3-D

["John A. Rupkalvis" <stereoscope@xxxxxxxxxxxxx>]

Greetings, Group!

Finally, I am getting back to answering the messages since I left.   I had
been out-of-town, very busy on a project, and only now have the opportunity
to reply.

First, I wish to thank all of you for the many kind messages (both on
photo-3d and the individual ones as well), as well as the helpful
suggestions regarding uploading the film images; this has been done.

Reviewing the numerous messages that traversed this site in my absence, I
find several fascinating threads of conversation.  Rather than attempt to
jump in and answer them individually, I am going to comment on some of them
to the group in general.

Eyestrain and anaglyphs.  Most eyestrain in all types of stereoscopic
display is due to image misalignment, or excessive parallax range.  This is
true of anaglyph images as well.  Color bombardment effects, well not truly
eyestrain (the eye muscles are not affected), nevertheless can result in
discomfort and even headaches.  These of course are specific to anaglyph
applications.

Anaglyph images are usually best when the differentiating colors of the
image match the viewing filters.  When projecting film images (slides or
motion pictures) far better results can be obtained by placing matching
filters in the light path than by trying to encode it onto the film itself.
For video projectors, some work better for anaglyphs than others, and should
be tested.  Computer monitors work much better than television receivers
(much better purity of the color phosphors).

I was amused by the various comments concerning Ray Zone and myself.  I am
sure that Ray knows many things that I don't know, and that I know many
things that Ray doesn't know.  And, I think that this is likely true of
everyone in the group as well.  We all have different backgrounds and
different experiences.   This is what makes a group like this so valuable.
We each can contribute, and we all can learn from these mutual
contributions.  Ray and I discuss and share our knowledge with each other
whenever we meet, and now we can share with each of you, as we both will no
doubt learn from each of you as well.

Regarding the Seagull and other multiple lens stereoscopic cameras:  In
general, the more lenses the better.  David Burder actually built several
multi-lens cameras out of Nimslos cut apart and attached together to make up
to, I seem to recall, 16 lenses in one multi-chamber housing.   The reason
that more lenses are better has nothing to do with the stereoscopic aspect
(we view the images of only one pair of lenses at one time from one position
when looking at a lenticular image).  However, as we move to a different
viewing position (or move the lenticular print or transparency), it will be
found that at some point or points the image, or parts of it, will appear to
jump laterally.   The number of lenses on the camera (combined with other
factors, such as lenticule pitch, size, distance, etc.) determines the angle
of view through which the image can be seen before experiencing this "jump".
All else being equal, more lenses results in more images that can be
sectioned, creating a smoother more continuous image impression.  Sort of
analogous to higher frame rates in motion pictures giving smoother appearing
images.

Yes, only 3 complete images per roll is a drawback.  Consider, however, that
many medium and large format cameras use cut film (sheet film) holders,
which only allow one (single sided) or two (duplex) shots per film load.
And, these have been used by professionals for years.

Some thoughts on the several missives (and missiles) tossed about regarding
film vs. digital imagery.

Photographic imaging systems have always involved compromises, such as grain
size and resolution vs. sensitivity (film speed).  In this aspect at least,
similar compromises exist with digital systems as well.  The number of
pixels and pixel size (and shape) have been equated with the number of
grains and grain size (and shape) in film.   As digital systems improve,
they are compared to a moving target.  Film quality continues to improve as
well.

Other factors are perhaps even more important as to the life of film as an
imaging medium.   Surprisingly (and perhaps, distressingly) resolution and
image quality are not the major factors in the marketplace that we would
like to think.

Several years ago, Kodak ran a market test experiment, in which they showed
amateur photographers and non-photographers (every-day people) images of
varying resolution and quality, and asked them what they would find
acceptable.   The general answer that they got was that if it was possible
to recognize a friend or relative in a photograph, the quality was "good
enough".   This survey had a direct bearing on the marketing of the 110
film/camera products.

Factors of importance are usually economic.  Consumer film cameras appear to
be diminishing as compared to digital (still and camcorder systems).  Yet, a
lot of film is used for theatrical motion pictures.  And, this market
probably will not disappear very rapidly.   There are a lot of theaters
equipped with film projectors.  A good film projector can be purchased for
about $1000 (I paid $500 for a used Simplex, including lamphouse, a set of
lenses, and all accessories).  It is not likely that smaller theaters (the
majority), especially in third world countries, will convert to digital any
time soon.  Most are on a borderline profitability basis right now (they
survive on the concessions).  Digital theatrical projectors will have to
come down from their six-figure prices a lot before most theaters can afford
to convert.  As long as theaters project it, Kodak will continue to make
film.

Synchronizing dual cameras.  Some time ago, I synchronized a pair of Olympus
OM-10 cameras with a wire link between the winders (sort of like motor
drives).   This worked quite well, but since I used this mainly for
hyperstereos of fireworks at night, people would tend to trip over the
wires.

So, I hooked up an RF link (radio controlled), and this has worked quite
reliably for the purpose.  As you can imagine, sync has to be quite accurate
when shooting fireworks hyperstereos.

Moisture on slides that are mounted in glass.   One idea is to pack your
slides with a packet of silica gel when traveling to humid areas.  Another
is to preheat the slides by placing the slide tray in the path of the
exhaust fan of the projector.  Condensation is a result of the slides being
colder, not warmer than the surrounding air.  This is why the condensation
diminishes while the slide is being projected.   IF you do preheat your
slides, check them frequently to make sure they are not overheating.
Usually they will be safe if you can comfortably hold the metal slide mount
in your hand.

Volumes have been written about visual defects that prevent stereoscopic
perception.  It is a very interesting field.  When the problem is
directional, prismatic correction is sometimes attempted, as well as reverse
correction as therapy.  One thing I have tried (with varying degrees of
success) is to use two separate monoscopic slide viewers, and mount the
stereo pair in separate 2x2 mono slide mounts.  That way, the person can
move them individually until the images fuse.  Usually, I start with a pair
that do not have any images other than an "X" or a "+" in the center, to
make it easy to find the best position.  Then I mount smaller images (as
from a Stereo Realist) in half of the slide mount, and a "+" centered
directly above the image in the unused area.  After enough practice, they
began to not require this "crutch".

Unfortunately, this method works sometimes, but not always.  An
opthalmalogist explained to me that part of the problem is motivation.
Often, if the individual has seen stereoscopically before, (such as when the
problem is a result of an injury or illness after maturity) they feel
sufficiently motivated to go to the effort of trying, recognizing that
patience is requisite.  If they have never seen in stereo, the motivation
may not exist.

Well, that's about as far as I have gotten reading the numerous interesting
exchanges since I got back.  I will read more tomorrow, and hopefully will
catch up on them all before even more come.

Thank you all so much for welcoming me into the group.

Sincerely,

John A. Rupkalvis








----- Original Message -----
From: "Ray Zone" <r3dzone@xxxxxxxxxxxxx>
To: <photo-3d@xxxxxxxxxxx>
Sent: Thursday, September 28, 2000 8:38 PM
Subject: [photo-3d] 15/70 3-D


> John Rupkalvis wrote:
>
> >Interesting dialog re: Imax 3D and the 65/70mm formats.   A little more
> >insight on the formats...<
>
> Ray Zone responds:
>
> Thanks for your input on 15/70 film, John.  I've never had an opportunity
to
> physically examine a release print of the IMAX 3-D film(s) to check out
> either the magnetic or digital track.  On page 106 of the September
American
> Cinematographer article on Journey of Man there is a frame of 15/70 IMAX
> (one half of a stereo pair) reproduced actual size.  But this is a contact
> positive on 70mm of a camera test so the soundtrack is not in evidence.
>
> I wasn't aware that you had restored "Spartacus."  A great thing to do!
> Regarding the two film clips you've attempted to upload:  I just visited
the
> photo-3d@xxxxxxx files and didn't see them.  I sure hope you upload 'em!
> Maybe just individual L-R frames at actual size with 72 ppi resolution
will
> get the file sizes small enough.
>
> Thanks again for posting to photo-3d.  This list will certainly benefit
from
> your years of experience in stereography.  Please continue to post.
>
>
>
>
>