Archived posting to the Leica Users Group, 2006/06/15

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Subject: [Leica] 24x36mm sensor for the RFDM
From: red735i at earthlink.net (Frank Filippone)
Date: Thu Jun 15 05:59:25 2006

Didier is 100% correct..... the implication ( logical implication not 
practical implication ) is that if Leica had decided to make a
Digi-M using more WA lenses, they should have picked the R lenses as target 
lenses... an R mount RF camera.

Interesting thought?

Frank Filippone
red735i@earthlink.net 

You ignore one problem. RF lenses and SLR lenses are absolutely not akin 
when it comes to the angle of the incoming light rays,
which is a crucial factor for digital sensors, but not for film emulsions. 
Many RF lenses protrude deeply into the camera body, and
the light that goes from the back side of these lenses to the corners of the 
24x36mm film frame, can have an angle significantly
lower than 90 degrees. Film emulsions react quite indifferently to this as 
the three-dimensional emulsion grains can be exposed from
the side, too. But a sensor needs the light coming in at a 90? angle, and 
does overproportionally underexpose the lower this angle
gets. 

SLR lenses have another design because of the mirrorhouse. They're more away 
from the film/sensor plane, and the angle of the
incoming light is straighter. This explains why a digital sensor in RF 
camera produces more vignetting than the same would in a SLR.
But nonetheless most SLR lens producers have redesigned their lens lines for 
this reason, and for the crop factor and have added new
coatings at the back side of the lenses to prevent light reflexions from the 
sensor. 








Replies: Reply from rangefinder at screengang.com (Didier Ludwig) ([Leica] 24x36mm sensor for the RFDM)
Reply from vondauster at earthlink.net (Will von Dauster) ([Leica] 24x36mm sensor for the RFDM)
In reply to: Message from rangefinder at screengang.com (Didier Ludwig) ([Leica] 24x36mm sensor for the RFDM)