Archived posting to the Leica Users Group, 2001/11/06

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Subject: [Leica] Re: Vs: Re: Digital Dreams - lengthy
From: Jim Brick <jim@brick.org>
Date: Tue, 06 Nov 2001 10:14:43 -0800

Actually, I referred to a Schneider white paper. I haven't read anything 
from Rodenstock.

Backs and cameras that utilize normal interchangeable lenses, have low-pass 
filters built-in to the sensor to make sure that the MTF of the sensor is 
at least twice that of the lenses. This way aliasing and other Nyquist 
artifacts are not a problem.

I believe that I stated the other day just how difficult it is to get the 
data out of the Philips sensor, intact, and sent on its way to the PRNU, 
interpolator and color space converter stages. And, of course, a 6mp chip 
will have a very low yield, which will keep the price of good chips way up 
there.

All the best!

Jim


At 06:48 PM 11/6/2001 +0100, Raimo Korhonen wrote:
>Dunno about snobbery but I did read the Rodenstock article recommended by 
>Jim and an interesting piece it is: it describes quite thoroughly why 
>ordinary good quality photographic lenses are not good for digital photography.
>It fails, however, to describe why the said lenses are good for digital 
>photography. This is a failure, because ordinary good quality lenses are 
>successfully used - and Rodenstock seems to be the only optical company 
>implying that inferior optical quality gives better quality digital 
>photographs - and even they do not explicitly state that their Digtar lens 
>line actually is inferior. The other company having introduced lenses for 
>digital photography - Sigma - only says that these lenses have better 
>evenness of illumination suitable for digital photography and shorter 
>focal lengths with larger apertures. Nikon, Canon, Contax support their 
>normal lens lines, so did Pentax. And Kodak Pro Back uses Hasselblad body 
>and lenses, not known for poor resolution or contrast.
>Aliasing is a problem in digital photography but it can be dealt with. And 
>CCD development is so far from theoretical limits that the chip that makes 
>Leica lenses usable for Rodenstock style - as opposed to more practical 
>approach - digital photography probably is not very far away. In the mean 
>time somebody should put his/her Leica/Canon EOS lens adapter to work and 
>try Leica lenses on a digital EOS. I´d bet that the results would not be bad.
>BTW I read from another list that the problems with the Philips 24x36 CCD 
>chip are not in the chip itself but complex programming it´s use requires 
>- and price. Might be true?
>All the best!
>Raimo
>Personal photography homepage at 
>http://personal.inet.fi/private/raimo.korhonen

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