Re: ASA/DOF/stereocameras

["The Photo-3D List" <photo-3d@xxxxxxxxxxxxxxx>]

Ted wrote:

> I wonder whether the f/1000 formula is applicable here.

A good question. I think we all tend to use it because of the 35 mm convention you discuss, 
and because it is the tolerance of the DOF table published in the realist manual. 
Personally, I find it a bit "soft" and prefer the f/1400 (and even f/2000!) tables which my 
old Leicas and Rolleis use, but this makes for some impractical shooting situations with a 
medium which demands lots of deep focus under most circumstances from 35 mm lenses.

> I had been told that the Revere used Cooke triplets, but i didn't realize
> all those other cameras did too.  Are there any other lens designs in
> use in stereo cameras, and how much does it matter, given the production
> tolerances of the day.

Realist 2.8s and Belplascas use four element in three group construction, the so-called 
modified Taylor type or tessar lens design. Does it make a difference? While is seems to on 
the whole, it may not in the case of your individual camera, because of the wide variation 
from example to example. We had a couple of excellent posts on this subject just recently, 
you may want to search the digests on the Bobcat ftp site.

Having shot with a belplasca and lots of different zeiss tessar lenses, my personal 
experience is that the zeiss tessars are notably more consistent in their performance from 
len to lens (more rigorous quality control?), and the design itself makes for results which 
are sharper in the corners. Your milage with realist 2.8s however is likely to vary 
considerably because of a number of different lens vendors, and lots of individual 
variation.

Somebody help me with this... I don't know of any other more advanced lens design which is 
found on stereo cameras. I think the FEDs use the 4-in-3 design. I'm not certain that the 
wollensak 2.7s even used tessars...

Bob Howard? Anybody?


Eric G.
egoldste@xxxxxx


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