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

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Subject: RE: [Leica] R8/R9 Digital Back announced
From: Aaron Sandler <aaron.sandler@duke.edu>
Date: Fri, 27 Jun 2003 13:09:51 -0400
References: <5.1.0.14.0.20030627110913.02739eb0@mail-aj.acpub.duke.edu>

Hi Austin,

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.)

Thanks,
Aaron


>   SLR wide angle lenses (which are of retrofocal design,
> > meaning they have elements designed to bend the light rays back
> > into being
> > mostly parallel with each other in order that the rays of interest still
> > all hit the film after travelling the additional distance to accommodate
> > the mirror) send all of their image to the film/sensor at a
> > pretty-close-to
> > perpendicular angle of incidence.  Therefore they work for film
> > and current
> > digital sensors.  Anyway, that's my understanding.
>
>Not quite.  It's the wide angle lenses that are the problem, and they, even
>for SLRs, still have vignetting problems with full frame sensors.  Why most
>digital SLRs don't show this problem is the sensor is in fact half the size
>of 35mm film...and therefore doesn't use the light outside that region.

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Replies: Reply from Aaron Sandler <aaron.sandler@duke.edu> (RE: [Leica] R8/R9 Digital Back announced)
In reply to: Message from Aaron Sandler <aaron.sandler@duke.edu> (Re: [Leica] R8/R9 Digital Back announced)