Archived posting to the Leica Users Group, 2003/06/27

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Subject: RE: [Leica] R8/R9 Digital Back announced
From: "Austin Franklin" <darkroom@ix.netcom.com>
Date: Fri, 27 Jun 2003 13:26:06 -0400

Hi Aaron,

> Thanks for confirming my basic understanding.  One question, though: It
> doesn't make intuitive sense to me that a retrofocal WA lens designed for
> SLR film (assuming it is able to light a 24x36mm square of film
> relatively
> evenly) would vignette on a 24x36mm digital sensor any worse than
> it would
> on the same area of film.  Can you "shed light?"  (Tee hee!
> Sorry, couldn't
> resist.)

The angle of light at the edges is NOT perpendicular to the film plane,
which for film, is not an issue...but for a digital sensor, which has the
sensing element, basically recessed into a square hole...where the sides of
the hole cut-off the light getting to the sensing element.  It's technically
called "well depth".

This is also one reason why Contax and Canon had to increase the size of
their lense mounts, and why Nikon does not have a full frame sensor...and
the new 14M Kodak camera does not perform well at all with wide angle
lenses.

Austin

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Replies: Reply from "A. Lal" <alal@duke.poly.edu> (Re: [Leica] R8/R9 Digital Back announced)