Eternally grateful for help on 47/5.6 SA and 35 Apo
Hoping someone can help me here. Regrets in advance for relative complexity - I have tried to be concise and clear.
I have a project camera and the need for a shuttered lens around 50mm or under in focal length (and ability to cover a diagonal of 98mm).
But the rear lens barrel at its widest/rearmost point must not exceed 40mm in diameter - OR - the lens must allow focusing at infinity with its rear barrel's most extreme point at least 32mm distant from plane of focus.
Potential candidates so far are:
1. 55mm Mamiya TLR taking/shuttered lens. This could work but won't give me full coverage. Relatively cheap also.
Question: Does "Back Focal Length" listed by Schneider (32mm) give me the 32mm I need above? I need to determine somehow what the difference in mm is between BFL (back element vertex to focus plane) and - the distance from rear lens barrel to focus plane. Are they the same or close to the same?
3. 35 Apo-Grandagon. The 35 Apo's rear lens barrel is listed at 60mm diameter. But I am unable to determine distance from the back of rear barrel to focus plane. I need at least 32mm or so minimum.
Short answer, a 47/5.6 SA won't do for you and a 35/4.5 Apo Grandagon is iffy.
I suggest that you design around lenses with known characteristics instead of in ignorance and hope.
Both of the lenses you asked about can be used on a humble Century Graphic. Or, for that matter, a slightly less humble 2x3 Crown Graphic. If you want to take pictures with either, just get a camera that can use it and walk away from your obsessions.
Re: Eternally grateful for help on 47/5.6 SA and 35 Apo
Hello Dan,
Much obliged for taking time to respond. I had the Apo link but it did not tell me all of what I needed to know. The Schneider link is very helpful.
You might have asked first, but I am working with an existing stereo camera. Thus, there is not opportunity to 'design around'.
It is not my own preference to mix disciplines, especially on a site focused on one particular. Thus, I am not sure what to do about your (extra-photographic) references to hope, obsessions. Interesting ideas these are, nonetheless.
Feel free to PM me to discuss those ideas if you feel the need.
A very bright poster once told me if I participated in a forum I ought to be prepared to accept responses I received - their being admixed with distantly off-topic ideas notwithstanding.
Re: Eternally grateful for help on 47/5.6 SA and 35 Apo
Well, explaining y'r project would have helped. If you want to receive help, help us understand what you're doing, don't leave us guessing or badgering you for more information.
I can't understand why back focus -- distance from the rearmost point of the lens assembly to film when the lens is focused at infinity -- can't be less than 32 mm if you're starting from a stereo camera. The things are just boxes with nothing much inside. Are you sure you're not thinking of the distance from the back of the shutter to the film plane?
What is your stereo camera's native format? I ask because I can't think of a stereo camera, except perhaps the multi-lens ones for lenticular stereo, that takes two images 50 mm long by who knows how high? Which stereo camera are you starting from?
FWIW, I'm still shooting a 38 Biogon on my little Century. Gives me nice long low shots, but they're not as long as I think you want. Just what size image on film do you want, anyway?
It seems to me that if your goal is to shoot roughly 90 degree images that cover a 4", more or less, circle then you ought to walk away from your stereo camera and get a press, field, technical, or view camera that will focus your chosen lens, shoot 4x5, and crop.
In other words, don't go crazy trying to make a bad solution give you what you want, go straight to a known good solution. Why work harder than necessary?
I think you've given us a good example of the corrupting influence of found money, sorry, found camera.
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