[filmscanners] Re: Pixels and Prints

["David J. Littleboy" <davidjl@gol.com>]

"Austin Franklin" <austin@darkroom.com> writes:
>>>>>>>>>>>>>
> How can a scanner have superior spectral response to a Bayer camera?

Unless all the sensors seen the same thing, they aren't seeing the same
thing.  In a Bayer pattern sensor, each sensing element is seeing different
light, unless there is a filter over the sensing elements that provides that
function.
<<<<<<<<<<<<<

Here's where we disagree: I don't see the lower spatial resolution for color
affecting the spectral resolution for color. The actual measurements are
identical (other than being first generation in digital, second in scans).

Note that even with three measurements at each point, the colors at features
smaller than the resolution of the system will be wrong. And there's always
an antialiasing filter. And we're looking at it with low-chrominance
(spatial) resolution eyes.

If you print a Bayer captured image at a dpi density such that the luminance
resolution is adequate, the chrominance resolution will be as well.

So for features large enough to see, the Bayer camera is providing full
color measurement. And with a lot lower noise than scanners.

>>>>>>>>>>>
  Also, they aren't really the same.  The scanner sensor is,
obviously, spectrally responding to the film.
<<<<<<<<<<<<

Which has already introduced infelicities in the spectral response.

>>>>>>>>>>>
Film also has a higher image density capturing ability, which current CCDs
do not, and as such.
<<<<<<<<<<<<

"image density capturing ability"???

If you are talking about dynamic range or latitude, the tests I've seen show
the dSLRs superior to slide film. If you are talking about a
per-unit-area-of -sensor comparison, dSLRs win in most comparisons I've
seen. Just thinking about an 8x10 made from a 22x15mm area of film is enough
to make one shudder.

Also, there's the issue of noise. Scanned film is a lot noisier than direct
digital capture. Just the noise problem alone makes scanned film problematic
for color reproduction: the bit depth after the noise is much less than
digital.

>>>>>>>>>>
  You also can't use Zone system compensation with an
original CCD, but you can with film, and therefore have a far larger B&W
image density range than you would with a CCD.
<<<<<<<<<<

DSLRs are certainly problematic for B&W, but you can't use Zone system with
color films (color shifts on push/pull), and you can't really use the zone
system with 35mm B&W (even N+1 processing makes the grain problematic and
N+2 is really unreasonable).

David J. Littleboy
davidjl@gol.com
Tokyo, Japan

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