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Old October 5th, 2017, 03:43 PM
Jerome Marot Jerome Marot is offline
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Join Date: Jan 2011
Location: Munich, Germany.
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Originally Posted by Doug Kerr View Post
Although I have regularly railed out against this validity of this notion, when dealing with the 36 mm × 24 mm still camera frame format, we tend to thing of a 50 mm lens as "normal". This is often related to the diagonal frame size, which it about 43.3 mm.

If we now move into the world of 16 mm cinematography, where the standard frame size is about 10.3 mm × 7.5 mm (a diagonal of 12.7 mm), we find that, for the Kodak cameras at least, it is almost universal to furnish them with a lens of 25 mm focal length. This yields a substantially smaller field of view than the fabled 50 mm lens on a full frame 35 mm frame camera.

On the 8 mm ciné camera front, where the frame dimensions are nearly half those in 16 mm work, it was very common to furnish the cameras with a 13 mm lens, the field of view being almost identical to that for the 16 mm cameras.

Do we have any idea what might have led to this custom?
Probably, the reason is that taking photographs is a bit different than filming a movie. Wide angles were not necessary for these cameras because:
  • one could not film inside without lights in that era and
  • for landscape, one simply pans the camera around.

On the other hand a longer focal was advantageous for portraits and generally for filming people. Also: the relatively low resolution of home movies made it necessary to fill the frame with the subject. Last but not least, a 100mm "kleinbild" lens is relatively large and 160mm medium format even more so. A 13mm film lens was not.
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