RE: Re:DigiCam file vs 35mm scan

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<x-charset iso-8859-1>> He seems to have found that 35mm fine-grain film such as Velvia only
becomes
> grain-limited at about 6000 ppi, but the resolution of that is pathetic
> compared to 4x5 scans.

The two are hard to compare.  As a note, the resolution of LF lenses pales
compared to 35mm lenses, which will resolve much more than an LF lense.  So,
just because you have more film are, doesn't mean there is a multiplicative
relationship with the actual amount of information you get.  It may be more
like 2:1 vs 4:1.

> His comparisons with digital cameras are limited, but he suggests that
they
> will have to reach between 10-17 Mpixels before they are as good as 35mm
> Velvia scanned at 4000ppi, and that they will have to reach 100's of
Mpixels
> before they equal 4x5 Velvia.

If you do the arithmetic, 4000DPI x 1 x 4000 x 1.5 (since a 35mm frame is
approximately 1" x 1.5") gives you 24M "dots" (for lack of a better term),
and you need three sensors/"dot" (at least) for three colors...so you would
need 72M pixels to 'approximate' a 4000DPI scan...  Caveat...color film has
dye clouds, which are random, as opposed to a digital image sensor, which is
fixed.

Also, you may not need as much color information as you do image luminosity
(?) data per pixel, so sharing color information amongst adjacent pixels may
or may not be a detriment, depending on the scene.


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