I've been wondering about that. Looking at the recently posted high res
scans, the amount of grain doesn't always seem to match the relative
speed/graininess reputations of the films. This link
<http://www.photoscientia.co.uk/Grain.htm> has more than you probably
want to know about grain aliasing. What struck me is that his tests were
at 2700 dpi (the best available at home in 2000) and he found that fine
grained films had no problems, but faster films often did. I wonder if
5400 dpi is a point where the effect starts popping up with finer
grained films. Twice the sampling rate, half the average grain
size................
In the mean time, back in 2720 dpi land, I've been getting some results
I don't much like from scanning a roll of Supra 800. I think I'll try
some tricks like slight intentional misfocus and see what happens to the
grain.
Moose
andrew.gullen@xxxxxxxxxxxx wrote:
>Caution though: as an article referred to a few months ago pointed out, as
>the sampling (scanning) frequency begins to approach the "frequency" of the
>grain, sampling artifacts can occur which magnify the apparent grain. Thus,
>you shouldn't stop adding resolution at the point where you "see" grain if
>you're going to do a piece of film justice.
>
>Does anyone know the average distance between "grain" clouds in Velvia?
>You'd need to sample at half this distance or better (as it isn't a simple
>sine wave) to avoid artifacts.
>
>
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