Hi,
I recently acquired a 15" f5.6 Tele-Raptar in barrel. Black, with a hood...(aerial camera version?)
I would like to use just the front group on the front of an Alphax #4 shutter ( It threads in perfectly).
My question is:
How does one determine focal length and aperture on just part of a tele-design lens?
My normal procedure for determining FL of a non-tele design lens is to put a lens on the camera, focus on a distant object, and measure from aperture to film plane...
That doesn't work with a tele design... is the "front group only" no longer considered a tele design?
So...the "FL divided by the aperture size as measured through the front element of the lens" measurement would be incorrect as a result, if the FL was measured incorrectly.
If anybody who has done this conversion could please help me out, I'd appreciate it...because I will need to make an aperture scale for the shutter.
I have searched the forum for info about this conversion, but haven't seen these questions addressed.
Thank you!
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