Archived posting to the Leica Users Group, 2001/12/28

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Subject: [Leica] Re: Dfinity was: New M ?? OT
From: Jim Brick <jim@brick.org>
Date: Fri, 28 Dec 2001 18:39:48 -0800
References: <5.1.0.14.2.20011228143052.039badd0@pop.alink.net>

The reason the Dfinity is delivering 16.8 mp is because it has three 5.6 mp 
sensors behind a very expensive 3-way image beam splitting prism. That's 
three sensors in one camera with a huge amount of electronics to support 
them. This is the only way to get high resolution, separating out the RGB 
colors so that each color is at full 5.6 mp resolution. But it still isn't 
16.8 mp of color image, it's 5.6 mp of color image. If they used one 
sensor, it would be 5.6/4 = 1.4 mp of true resolution. Single full color 
sensors have one red, two green, and one blue pixel for every "color" 
pixel. So the true resolution is divided by four. The Foveon has one red, 
one green, and one blue sensor.

CMOS sensors have come a long way over the past two years. Two years ago 
they were really crappy. The push for them was because they are cheaper to 
make, take less power to run, etc. It has nothing to do with the number of 
pixels per sq. in. That is a limit of the semiconductor fabrication process 
and the fact that "each" pixel, regardless of whether it is CMOS or CCD, 
requires a photo transistor, exposure gate, storage capacitor, readout 
gate, and a few other miscellaneous parts. This takes a lot of space. And 
if you try to build them smaller, the noise goes up, the fidelity and 
dynamic range goes down. Not exactly what photographers want. So the lower 
limit for a good photograph is around 3 sq. microns for a pixel. That's 36 
sq microns for a complete color pixel. Really big compared to film. And is 
why sensors equalize out all lenses. A Leica lens will be equal to a Sony 
lens. You will not be able to distinguish between them when using a digital 
camera.

Jim


At 05:53 PM 12/28/2001 -0800, rp johnson wrote:
>Jim Brick wrote:
>
> >
> > It's not really a Hasselblad camera, it's a Hasselblad - Foveon joint
> > venture. Read about it here:
> >
> > http://www.hasselbladusa.com/about/pr092000d.htm
> >
> > Jim
>
>Thank you, Jim,
>
>So it is sort of "old" news.  But it was new to me.  Now I have another
>question:
>
>I really learned a great deal from your postings on digital and its
>limitations vs. film and why we are not likely to see 6m pixel M6's in the
>next two months, but the Dfinity is delivering 16.8 m pixels (according to
>the releases).  I get the impression that you were speaking primarily to
>the limitations of CCD technology earlier.  But can you say that CMOS based
>digital cameras are likely to be the ones that deliver the mythical
>"digital M6" in the near future?
>
>Thank you,
>
>RP Johnson
>
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In reply to: Message from Jim Brick <jim@brick.org> ([Leica] RE: New M ??)