cuthbert
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- Joined
- Nov 16, 2014
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- 35mm
OK, I'll shut up about this eventually, I promise, but...
OK, so we know that Oskar Barnack decided that the 35mm cine frame was too small. So he doubled it, to 24x36mm. So, what "normal" lens to use? He just doubled that too, obviously, from 25mm to 50mm. Here's where it gets weird: the expected "normal" lens (the diagonal of the frame) for the 35mm cine frame is an exact 30mm. 25mm is a bit wide. With the doubled width of the 35mm still frame, the doubling of the "normal" cine lens comes out a little too long, 50mm vs ~43mm.
So, it would seem Barnack either a) made an arithmetic mistake when he established the new frame size and just doubled the "normal" lens size; b) knew and didn't care ("everybody is using the wrong normal already, what's the difference?"), or c) the idea that "the normal lens is the diagonal of the frame size" was thought up AFTER Barnack. Anybody have any idea which might be the case? I must be shouting into the void at this point, but I think it's an interesting historical question.
Re-read my post, he didn't make any mistake...he wanted to have a "real life" image magnification.
Cinematographic lenses don't have that requirement because the camera man is not supposed to shoot with both eyes open.