Archived posting to the Leica Users Group, 2003/09/01
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At 10:08 AM -0400 9/1/03, LRZeitlin@aol.com wrote:
><< Leica: A digital camera or back using the existing Leica M-lenses is
>presently not possible because of the short lens to film plane distance. >>
>
>
>This is Leica speak for saying we have no plans to implement a digital Leica
>M. To say that the rear focal distance is too short is nonsense. The distance
>between the rear element and the film plane is significantly greater than 16
>mm in all but a few extreme wide angle lenses. Don't believe me. Mount a lens,
>open the rear inspection door, and, usung a plastic ruler measure the distance
>to the film plane. In most cases the distance will be over 30 mm. Further the
>grazing angle applies only when a full frame CCD sensor is used. Most digital
>cameras that adapt film lenses (Canon, Nikon) use partial frame sensors that
>serve to increase the apparent focal length by 30 to 50%. Even if a full frame
>CCD were used, a simple plastic overlay lens on the sensor could correct the
>problem.
>
>Let's face it. The Leica M is at the end of its development as a useful
>photographic instrument. It is being marketed as a piece of prestige
>photographic
>jewelry. Leica is speaking with a forked tongue.
In terms of today's technology, Leica is right and you are wrong.
Leica lenses of 50mm and shorter have a much greater angle of
incidence in to corners of the frame than SLR lenses, and those are
the lenses of interest. Which Leica M user would accept being able to
use all their lenses.... except those of 50mm and shorter. 'A simple
plastic overly lens' is ridiculous; DSLR sensors use microlenses over
each photosite to compensate for the fact that all image producing
rays do not come in _parallel_ to each other, but there are severe
limits on this form of compensation; just look at the colour fringing
problems that Canon 1Ds users encounter with various wideangle
lenses. Those lenses are strongly retrofocus, with exit pupils much
further from the film plane than even Leica's 50's.
Even if 35mm lenses could be used, which Leica user would accept
having their 35/1.4 turn into a 53mm lens?
Whether the Leica M is at the end of its development as a useful
camera, is a completely different issue.
- --
* Henning J. Wulff
/|\ Wulff Photography & Design
/###\ mailto:henningw@archiphoto.com
|[ ]| http://www.archiphoto.com
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