P3D Re: Twin rigs Flawed?

[Brian Reynolds <reynolds@xxxxxxxxx>]

Boris' comparison centered on 35mm twin rigs for novices.  I thought
that as a recent novice (I started shooting with a twin rig in
April/May 1997) I would mention Medium Format (MF or 120 format)
twin rigs for the novice.  After all if the higher resolution
available from a 2x2 (inch) slide (as compared to an approximately
half frame Realist slide) is worth going for, imagine the improvement
with a 6x6 (cm) slide.

By the way, all of this is from my personal experience.  My opinion
of the success of this technique is based on the strong, favorable
reactions I get from everyone I've shown my slides to.

Boris Starosta wrote:
>
> "Twin rigs Flawed?"
> 
> Twin rig drawbacks:
> 
> Difficulty / cost of initial setup, purchase:
> -if you start with zero cameras, it will likely
>    cost more to set up your rig (than a Realist camera).

I started with zero MF cameras (for the past couple of years I've
shot 4x5), but was able to buy a pair of Russian Lubitel 166U's for
$40/camera.  These are plastic Twin Lens Reflex (TLR) cameras with
(nice) glass lenses and almost no quality control.  The low cost of
the cameras is why I decided to buy two of them and try stereo
photography on my honeymoon.  You can see some test pictures (shot
in B&W for stereocards) taken the weekend before my wedding on my
web page.

You can find bargains on used TLRs of better quality (e.g., the
older Yashicas and Rolleicords), but they probably won't be that
cheap.  Porter's (see <URL:http://www.porters.com/>) sells Chinese
TLRs (no longer being manufactured) for about $60, but I don't know
how good they are.  You might be able to find good Yashica A's or
Yashica D's for about the same.

> -Unless you make your own bracket, expect to
>    pay $50-$100 just for that. It's easy to make
>    your own, however.

I bought a Hama Twin Flash Bar at a local (NYC) camera store for
about $20.  My interocular spacing is about 9cm at the minimum and
can be increased to about 15cm for hyperstereos.  I shoot a lot of
landscapes, so I don't really mind the wide spacing.  Since I shoot
6x6 (the square format) I don't worry about camera orientation.

A recent check showed that I could mount my Pentax K-1000SE
(currently out on loan to a friend) and my Pentax ME Super on this
bar for landscape views.

> -you need to match lens f.l.
> -you need to match lens apertures
> -you need to match camera body shutter speeds

I didn't bother doing any of this.  I later discovered that one of
my cameras has a shutter that is slow by at least one stop (based on
looking at the processed slides).  This doesn't seem to effect the
final stereo pair.

> Thus, 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.
> 

I took the "Don't worry, be happy" approach to all of this.  It
worked out for me.

> Difficulty during "slide production":
> -synchronizing shutter requires twin release.
>    Difficult with flash, unless cameras are electronic.

On my honeymoon I used a pair of cable releases held in one hand
pressed together.  The cable releases were an additional expense as
I did not trust the cheap cable releases that came with the cameras
(and they were too short).  It worked often enough not to be a
problem.  The cameras (and my in experience with them) were flakier
than the cable release set up.  I eventually bought the Olympus twin
cable release for about $40.

Flash synchronization is less of a problem with twin TLR's than it
is with twin 35mm cameras.  Since TLR's use shutters mounted in the
lens (as opposed to focal plane shutters that modern 35mm cameras
use) they can sync to electronic flash at any speed.  Getting both
cameras to sync together is still an issue with electronic flash.
Using flash bulbs (remember the age of most of these cameras) would
probably lessen the difficulties.  Flash bulbs burn for much longer
than electronic flashes do, so synchronization is less of a
problem.  Note I do all of my photography with natural light or
"hot" (constantly on) lights, so I haven't played with this yet.  A
friend of mine organizes vintage dances (1860's through 1890's) so I
will eventually try some flash photography with my twin MF setup.

> -weight and bulk: even small "Point and Shoot" (P+S)
>    twin rigs are going to be relatively big.

Being mostly plastic my twin MF rig probably weighs less than some
modern 35mm cameras.  Even my 4x5 camera weighs less than a Nikon F5
with power winder and telephoto lens.

> -handholding is very difficult, unless your rig
>    uses two fully automatic cameras.
> 

I use a thin camera strap (I can't stand the thick ones, they're too
stiff) mounted on the right lug of one camera and the left lug of
the other.  Since I'm using a wait level finder this works out
fine.  People without previous TLR or large format ground glass
experience might be initially confused by left/right reversed view,
but you can quickly get used to it.

> 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.

The Lubitels do not have light meters.  Other (more expensive) MF
TLRs do (e.g., the Yashicamat 124G).  I use the Pentax spotmeter
that I also use for my 4x5 work.  Inexpensive handheld meters are
readily available from Adorama and B&H.

> -you get a choice of f.l. lenses.  Use zoom, carefully.
>    (Although we advocate shooting just 50mm
>    for regular pictures.)
> 

Most TLRs have a fixed lens (the Lubitels are 75mm, others tend to
be 80mm).  The Mamiya C330 TLRs have interchangable lenses, but are
considerably more expensive ($200-300/camera and lens).

> The 2x2 format stereo pairs produce superior views, and
> make for easy "post-production":
> -you can get very large views in an inexpensive viewer
>    (orthoscopic if you shoot w/50mm lenses).  Apparent image
>    will be up to twice as large as with cheapo Realist viewer.

I initially used a cheap cardboard fold up viewer that I bought from
American Science & Surplus with a set of computer generated stereo
views of mathematical wireframe surfaces.

> -if you toe in judiciously, you get slides back that are instantly
>    useable in a viewer.  No remounting needed.
> -No remounting means less cost and time spent in "post-production"

MF film does not normally get mounted, so you do have to mount your
own pairs.  It's not very hard.  I think that the large size of the
slide (compared to the miniature formats) probably eases the effort
required in mounting. I use the 6x6 mounts sold by Rocky Mountain
Memories (see <URL:http://www.frii.com/~rkymtmem/>).

> -Duplication of 2x2 slide pairs is relatively easy.
> 

Duplication of 6x6 slide pairs is expensive.  There is no MF
duplicating film.  To get duplicates they have to be reshot onto
either 35mm or 4x5 film.

> Standard American Realist format drawbacks:
> 

MF format stereo has all of the same drawbacks as 1950's era stereo
cameras, in addition to having to do everything yourself.

> -Quality viewers are quite costly, and still do not supply a view that is
>    orthoscopically correct.  (i.e. there is slight spatial distortion)

With Alan Lewis' MF viewer kit a very high quality viewer is readily
available (with not too much work) at a reasonable price.  Good
lenses cost money.  This viewer will be distributed by Rocky Mountain
Memories.

Another drawback of MF stereo is projection.  The standard MF stereo
mount can not be used in a commercial MF projector.  If the slides
are mounted for projection you will not be able to hand view them.
New MF projectors are also very expensive.  Older ones (from the
1950's) can be found for less money.

> Standard American Realist format advantages:
> 
> -Only within the Realist format can you obtain commercially made high
>    quality viewers.  Inexpensive 2x2 slide viewers give a good 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).
> 

See my comments above about Alan Lewis' MF viewer kit.  The work
required to build this kit is probably about the same as that
required to clean and modernize a Realist viewer.

> 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 because of small image size, and a distorted
> (stretched) spatial field.  This is the camera for impromptu family and
> vacation picture taking.
> 
> 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).
> 

Go for a MF twin rig if you want large slides (3.5 times more area
than a 8 perf 35mm frame) that will knock your socks off.  You'll
have to do a lot of work yourself (e.g., building a good viewer),
but it's a lot of fun and the final images can't be beat.  At least
not until you get into large format stereo.  :)

> Additional comments and sources regarding the 2x2 format twin-rig:
> 
> It is often said that the photographer cannot get the correct interocular
> (i/o) spacing, when shooting with a 35mm twin rig.  I disagree.  Shooting
> with two older style SLRs (i.e. they are not exactly small), mounted base
> to base (vertical portrait format), I get the same i/o spacing as the
> Realist: 70mm.  If you shoot with your two 35mm cameras mounted landscape
> format (horizontally), you can mount them staggered, one behind the other,
> to get _close_ to standard i/o spacing.
> 

You can find the Sputnik (a Russian MF stereo camera) for sale used,
but it will probably require some work as they have several problems
(light leaks and a shiny interior that causes loss of contrast
because of flare).

Several people (among them Alan Lewis and Sam Smith (see
<URL:http://www.arlington.net/homes/dlewis/> and
<http://www.cadvision.com/3dhacker/> respectively) have built MF
stereo cameras from individual mono MF cameras with the correct
interocular spacing.  This is not for the faint of heart, but it can
be done.

> The Pinsharp viewer can be obtained from Reel-3D Enterprises.  Look at
> <A HREF="http://www.stereoscopy.com/reel3d/slide-viewers-twin.html">
> 

I think Reel-3D also sells the cardboard fold-up viewer I mentioned
above (without the computer generated cards).

-- 
Brian Reynolds                  | "Humans explore the Universe with five
reynolds@xxxxxxxxx              |   senses and call the adventure science."
http://www.panix.com/~reynolds/ | - Edwin P. Hubble


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