At 11:32 PM 7/16/03, Joel Wilcox wrote:
Except that 100F also doesn't resolve as well as Velvia 50, according to
the Pop Photography review this month (81 lines to 100F's 72 lines).
Joel W.
I think this is what he said, although the sentence was long with fair
number of pronouns (can cause ambiguities). In any event, their respective
MTF curves explain why this is.
I omitted my understanding of how to interpret MTF graphs in my previous
posting (mea culpa). Look at the curve from about 10 lppmm through about
40 or 50 lppmm. IIRC, Velvia 50 actually rises above 100 0.000000or a portion of
this region. Those films (and print materials and lenses) that have a very
high curve in this region tend to have higher accutance; i.e. they are
capable of producing photographs that look sharper. This is in spite of
how the curve rolls off in the high lppmm.
What you end up with in a print is not just the MTF of the film. It's the
combined MTF of the entire system of camera lens, film, enlarger lens and
print material (emulsion). Anything and everything that has its own MTF
affects the final outcome.
In projecting slides, its camera lens, film and projection lens. Screen
surface also has an effect, but doesn't have an MTF per se. It's more like
print surface finish; glossy shows higher detail than matte. A pure white
matte screen will show more detail than a glass bead, at the cost of
reflectance for which glass bead is the highest of standard screen materials.
Keep in mind the entire system when striving for highest possible accutance
in a photograph. The highest accutance film cannot compensate for a low
accutance camera lens. If the camera lens doesn't project as much or more
detail level to the film plane as the film can record, the film cannot
record it.
-- John
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