P3D Re: Twin SLRs

["Dr. George A. Themelis" <DrT-3d@xxxxxxxxxxxxxxxxxxxxxxxxxxx>]

>>It seems to me that some people see Twin SLRs as a replacement for a 
>>Realist, etc.  I'd say, forget it!
>
>Does the article give any reasons for this statement?  If people are using 
>twin rigs, and liking the results, why would you or the author discourage them?

How can we discouraged someone who uses the system and gets good results?
The one that might be discouraged is the person who is thinking of using
twin SLRs to replace a stereo camera.  A stereo camera has three things
that twin SLRs do not have:

1. Synchronized shutters
2. Matching lenses
3. "Norman" stereo base (interocular of 60 to 70 mm)

Through trial and error you could get close to achieving 1 and 2.
#1 is only statistically achieved, i.e. 80% of times the shutters 
are synchronized at 1/500 s speed.  For someone like myself who 
takes slides and mounts them in 41x101 stereo mounts, #3 is never 
achieved.

As Allan Griffin said, and I agree, twin SLRs shine in cases where
you want to photograph action stereo using longer lenses and lightly
longer stereo bases or hyperstereos with longer stereo bases and any
lenses.  For a normal scene with a depth range spanning from 7 feet to 
infinity, nothing beats the convenience of using a stereo camera, IMO.

Also, to use the twin SLRs foolproof, you will have to use them in
manual exposure and manual focus.  With the automations out of the
window there is less insentive to use them as a replacement for
a mechanical stereo camera.

George Themelis