P3D stereo slide format comparison

[boris@xxxxxxxxxxxx (Boris Starosta)]

>From: fj834@xxxxxxxxxxxxxxxxxxxxx (Dr. George A. Themelis)
...
>For those who do stereo for their own enjoyment, the 101x41 format
>is definitely very convenient.  Plus, you can find good viewers for
>a reasonable price.

This is my cue for re-posting a comparative analysis of two types of stereo
camera processes, which also illuminates the differences in the stereo
slide formats.  It is to be understood that the presentation format is not
strictly dependent on the taking camera - however, a 35mm twin-rig camera
naturally lends itself to the production and post-processing of 2x2 mounted
slide pairs.

R E A L I S T / T W I N - R I G  R E C A P

We attempt to consider in a balanced fashion the advantages and
disadvantages of shooting stereo slides with either a twin rig (two 35mm
cameras mounted together on a bracket) or a Realist format camera.  We
assume that if you shoot with a twin rig, you will have your films
processed and mounted as you would any ordinary roll of slide film - in
standard 2x2 (50mmx50mm) mounts; and if you shoot with a Realist type
stereo camera, that your final mount is a "Realist format" mount -
41mmx101mm.

It is understood that customization of equipment is an option for both
modern 35mm cameras, Realist cameras, as well as the stereo slide viewers
involved.  However, for the purpose of this comparison, which is aimed at
assisting the novice in making a decision among lowest cost options, we
assume minimal customization of the equipment.  (Of course, a twin rig
represents a minor form of customization in and of itself.  But here we
assume twin rigs comprised of standard 35mm cameras).

This comparison assumes you are shooting for
stereo slides.  Some of the points will also apply
to those who wish to shoot for stereo cards.

Twin rig drawbacks:

Difficulty / cost of initial setup, purchase:
-if you start with zero cameras, it will likely
   cost more to set up your twin rig (than a
   single Realist camera).
-Unless you make your own bracket, expect to
   pay $50-$100 just for that. Easy to make your
   own, however.
-you need to match lens f.l.
-you need to match lens apertures
-you need to match camera body shutter speeds

Setup of a twin rig takes some time, and an
understanding of optics, cameras, and stereo.
Also maybe some service work by a dealer,
unless you buy new cameras.

Difficulty during "slide production":
-synchronizing shutter requires twin release.
   Difficult with flash, unless cameras are electronic.
-weight and bulk: even small "Point and Shoot" (P+S)
   twin rigs are going to be relatively big.
-handholding is difficult, unless your rig
   uses two fully automatic cameras.

Twin rig advantages:

Ease of use / flexibility during "slide production":
-You can twin fully automatic cameras.  Shoot easily
   with auto exposure, focus, wind, etc.
-At least you can get a light meter in the cameras.
-you get a choice of f.l. lenses.  Use zoom, carefully.
   (Although we advocate shooting just 50mm lenses for
   regular pictures).

The 2x2 format stereo pairs produce superior views, and
make for easy "post-production":
-you can get larger views in an inexpensive 2x2x2 viewer.
   (orthoscopic if you shoot w/50mm lenses).  Apparent
   image will be up to twice as large as with the cheap
   plastic-type viewer for Realist mounts.
-if you toe-in your cameras judiciously, you get slides
   back that are instantly useable in a 2x2x2 viewer
   - with a good stereo window.  No remounting needed.
-No remounting means less cost and time spent
   in "post-production"
-Duplication of 2x2 slide pairs is relatively easy.
-Scanning of 2x2 slide pairs is easy.


Standard American Realist format drawbacks:

Possible difficulties/risk in initial purchase:
-the camera will be old.  Might be in need of overhaul.
   Probability of mechanical bugs is moderately higher
   than with twin rigs using modern and new equipment.

Difficulty during "slide production":
-the older cameras are not automatic.  The Realist
   does not have a light meter in the camera.
   (I don't know about the others).  This will be
   important to snapshooters who don't want to mess
   with setting exposure and focus manually.

Difficulty / cost in "slide post-production":
-Only a few processors will also mount the stereo slides.
   This will generally cost extra, and you will not get
   your film back for a couple of weeks.  Or...
-Film from a Realist type camera must be returned from
   a regular processor uncut, as a long strip.  You must
   use a film cutter, and mount the two appropriate
   "film chips" in a Realist format stereo mount.
   Although mounting gets easier and faster after you
   learn it, it still takes _some_ time.  Cleanliness
   and careful film handling are important.
-Mounting supplies cost some money.  Easiest to use
   mounts (such as RBT) will add considerably to the
   cost of each slide.
-Slide duping is more difficult and costly to obtain.
-Quality Realist format viewers are quite costly,
   and still do not supply a view that is
   orthoscopically correct.
-Inexpensive viewers will give a small anddistorted view.


Standard American Realist format advantages:

Portability / reliability during "slide production":
-The Realist camera itself is very robust.  Other
   cameras in the format perhaps less so, but probably
   still better than most twin rigs.
-Any Realist type camera will be far more portable.
-Although manually set, focus and exposure will
   be synchronized.
-Flash synchronization is no problem.
-Handholding is no problem.

Realist advantages in "post-production":
-Realist format slides are universally recognized
   and accepted _within the community of stereo
   enthusiasts_.  More easily sold to collectors?
-Only within the Realist format can you obtain
   commercially made high quality viewers.  2x2 slide
   viewers give a high quality view because of the
   larger size of the slide and better focal length
   matching.  But the best optics are found in Realist
   compatible viewers (such as the Red-Button).



Summary:

Get a Realist type stereo camera, if you want a compact, robust camera, and
don't mind paying a bit of money for a good image in a superb viewer
(Red-Button).  It will not be possible to obtain a truly orthoscopic image,
unless you customize either the camera or viewer.  Cheap viewers for this
format are disappointing.  This is the camera for impromptu family and
vacation picture taking - just don't expect to be able to easily dupe and
distribute your slides to other members of the family.

Go for the twin rig, if you intend to distribute your slides to others
without their own viewers.  This might be the case for serious hobbyists
and artists.  Duping will be easier, and supplying decent viewers to those
who will receive your slides will be far less costly.  Although the images
obtained in these viewers may not be optically perfect, they will be larger
and truly orthoscopic, if you shoot with 50mm lenses (Notwithstanding its
name, the "Pinsharp" viewer is slightly blurred here and there, and has
some chromatic aberration).


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Boris Starosta            boris@xxxxxxxxxxxx
                          http://www.starosta.com
usa 804 979 3930          http://www.starosta.com/3dshowcase



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