Would anyone care to comment on the following extract from this link (firstly, whether it is in fact true).

http://mejac.palo-alto.ca.us/leica-users/v21/msg03076.html

"In film, a 1 micron square silver halide grain contains 20 Billion silver halide molecules, each capable of being hit (exposed) by a photon. It only requires three being hit to produce a developable speck. A digital sensor pixel (the minimum recording spot) is 5 microns square (25 sq. microns vs 1 sq micron) and will ultimately report a light level of 0-255 (256 levels) for this whole vast area of 25 sq. microns. This is why Leica lenses out perform most other lenses on film, but are no better than anything else on pixels. And why film can record deep shadows and bright highlights in the same scene. Digital sensors cannot. All fine detail (Leica's strong point) is completely lost."

Does this explain the difference between film and digital adequately enough?

Thanks,

-- Vikram (VSingh493@aol.com), March 15, 2002

Answers

No, it does not, the quote is quite meaningless. What does the number of atoms contained in film have anything to do with digital quantization? In fact, there are 1250 quadrillion light sensitive silicon atoms in each 25 sq um pixel (1.253 x 10^18 to be exact), which works out to about 62 million times more than 20 billion. The comment about digital sensors inability to record shadows and highlights in the same scene is equally ridiculous.

-- Bert Na (bergna@yahoo.com), March 16, 2002.

The only thing I can think of is noise floor.

-- Vijay A. Nebhrajani (vijay_nebhrajani@yahoo.com), March 16, 2002.

I'm kinda slow when it comes to digital but it would seem to me irrelevant how many atoms are in a pixel when the finest definition will never be smaller than the size of that pixel--which is not the case with film.

-- dave yoder (lists@home.com), March 17, 2002.