I would be interested also. I've never seen an MTF
test of the 21/3.5. Usually these test measure
contrast with using a specific slit width or a line
pairs if 30 lp per mm or a set of line pair at 10
lp/mm, 20 lp/mm and 40 lp/mm. I find that I am very
satisfied with any lens with contrast greater than 50%
at either 30 lp/mm or 40 lp/mm.
Warren
<<<From: Chris Barrett <cpbarrett@xxxxxxxxxxxxxxx>
Dear Cy,
"I looked at the magazine article again. The charts
in the article show ="MTF measurements", but precisely
what those measurements represent is not specified.
The MTF values are percentage values plotted on
the Y axis on the chart (which ranges from 0 to 100%).
These percentage values are the values that I showed
in my previous posts. I guess that the values =
plotted are for some particular spatial frequency (or
perhaps an average of several different spatial
frequencies), but this is not specified in the
article.
The article reviewed the 21mm f3.5, 24mm f2.8, 50mm
f1.8, 50mm f2 macro, 85mm f2, and 200mm f4."
It sounds like an MTF value, but it would have more
meaning with the spatial frequency. OK for a
comparison between lenses tested and presented the
same way.
Is there any chance of sending me the data on the 24mm
2.8? Or could you scan the whole article?
Chris>>>
=====
Warren Xato
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