RE: [Leica] Re: Re: Vs: digital

["Wang, Albert" <Albert.Wang@ibx.com>]

Amen, Jim! That's the best explanation I've heard about not having a digital
M camera :)... Gives us eternity to shoot film for the rest of the Leica
lives together! :)

Alfie

- -----Original Message-----
From: Jim Brick [mailto:jim@brick.org]
Sent: Monday, November 05, 2001 12:40 PM
To: leica-users@mejac.palo-alto.ca.us; leica-users@mejac.palo-alto.ca.us
Subject: [Leica] Re: Re: Vs: digital


At 06:56 AM 11/5/2001 +0000, George Day wrote:

>"not compatible"?  Whatever. Seems to work just fine for the well over 90%
>of photojournalists shooting Nikon and Canon digital.  I'm sure it would be
>quite adequate.  These are lenses, not spiritual beings.


Unfortunately, George, you are not aware of the technology involved in 
digital sensors and lens resolution/MTF frequencies. Instead of me 
attempting to explain all of this to you, go to:

http://www.schneideroptics.com/white/kina.htm

and see why Schneider (and Rodenstock, and others) make lenses DESIGNED FOR 
digital sensors.

Then go read about the Nyquist limitation at:

http://www.opus1.com/~violist/help/nyquist.html

Nyquist's theorem: A theorem, developed by H. Nyquist, which states that an 
analog signal waveform may be uniquely reconstructed, without error, from 
samples taken at equal time intervals. The sampling rate must be equal to, 
or greater than, "twice" the highest frequency component in the analog
signal.

In terms of lens resolution on digital sensors, it means that there must be 
at least twice as many pixels per mm as the maximum resolution (lp/mm) of 
the lens. If this is not true, the information gathered will be either 
partially or completely in error, and always aliased. See figure 4 in the 
Schneider white paper. Modern Leica lenses have more resolution than can be 
handled by digital sensors. They cannot make pixels small enough to be at a 
frequency twice that of the resolution of Leica lenses. Five square microns 
is about the limit of a pixel that can record enough light to produce a 
quality dot. And don't forget that it takes four pixels to record a single 
COLOR dot (pixel).

The problem is that folks who do not understand the limits of digital 
electronics vs analog signals are moaning and groaning as to why Leica 
doesn't get with it and produce a digital M mount camera. They could 
certainly OEM a high level digital camera and put an M mount on it. But 
why? They would also have to but a resolution reducing filter behind the 
lens in order to produce good digital photographs. So why bother? The 
Panasonic Leica digital camera soon to be on the shelves has a Leica lens 
which is specifically designed to match the resolution capabilities of the 
digital sensor.

There is no full size digital sensor made with a pixel size small enough to 
take advantage of Leica lenses. Actually the reverse is true. Leica lenses 
will cause the recording of false information via these sensors.

There is certainly more to it that simply bolting an M lens on to a camera 
containing a digital sensor.

Over and out!

Jim
  

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