Auflagemaße für den Visoflex I und den Visoflex II, III?

SCFR schrieb:

Hallo,
Könnte mir jemand das exakte Auflagemaße für den Visoflex I und den Visoflex II, III nennen?
Danke für Eure Hilfe.

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Film is put through the camerabody inside a film channel (invented by Zeiss and not used in the TM Leica bodies), comprising an outer guide rail, and an inner rail. The film is held in place by the outer rails and the pressure plate that rests on the outer rail. The inner rail should hold the outer edges of the film in a flat position. BUT: The distance between both rails is 0.2mm. Exact distances vary as manufacturers have different tolerances. But on average a film has a thickness of 0.13 to 0.18mm. Thus the film has a clearance of 0.02 to 0.07mm and this is enough to jeopardize ideal film flatness. Films tend to bulge forward.
So the designer has some options when he has to locate the exact focal plane for his lens. Use the outer rails (lens flange to pressure plate distance) and be sure that you will miss the emulsion of the film where the image should be located. Use the inner rails and the flatness of the film is a problem. So here we have the real problem of locating the image plane. Every manufacturer has its own ideas and in the case of Leica they have deceided that a distance of 27.8 mm from the bayonet flange will locate the image plane inside the film gate dimensions and take care of the curving of the film it self. The wellknown dimension f 27.8mm is often described as the flange to film plane distance. Correctly described iwe would have to say: distance from flange to focal plane, which might be identical to the film plane under a certain set of assumptions.
Let us look at actual figures. In the leica M-series the distance from bodyflange to outer film rail is 27.95mm. The thickness of the film channel is 0.2mm. (I measured 0.21mm). So the area where the film might be located ranges from 27.95 to 27.75. With a lensflange to focal plane distance of 27.80mm the lens, when correctly adjusted would focus onto the film emulsion layer.

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