At 09:11 PM 9/19/2003, Julian wrote:
><snip>
>The analogue cameras need an anti aliasing filter (always formed by the
>lens) to avoid base - fog increase. This has been one of the limits to 35mm
>lens performance for decades, with cost being another. The
Aliasing is an artifact of uniform sampling of information with higher
frequencies than the sample rate. Low pass (anti-alias) filtering
minimizes high frequencies from creating lower frequency patterns
through sampling. Film samples, in the sense that it has grain
structures, but grains are not uniformly spaced and overlap, so the
effect of grain randomness is simply the spreading of the noise
frequency; that is, it is indistinguishable from just the grain noise
itself and highly unlikely to be affected by lens sharpness. The
sharpness is simply lost in the grain resolution. Hence, I don't think
the sharpness of a lens is going to increase or decrease fog, ie.
noise, from film grain sampling. Light scattering in the lens is much
more likely to increase fog. I can't figure how an analog camera would
need anti-aliasing from of an overly sharp lens. I've never heard of
such a thing. Perhaps I am not understanding something?
Wayne
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