Marechiare wrote:
> It clearly points out "You shouldn't stop down beyond f/16 due to the
> limiting effects of light diffraction." That's why I persist with my
> point.

That's one lens with a exacting test done in the lab specifically looking
for diffraction effects.  Even this test showed little degradation at f/16.
If I remember right, you were claiming problems at f/11.  Keep in mind that
diffraction is always there, the question is when it becomes significant
enough to matter.  Obviously that is somewhat subjective.  Note that this
test skipped every other F stop.  The next data point they showed was f/32.

Obviously the diffraction effect at f/22 will be somewhere in between.
Clearly it is possible to measure this in a lab, but I think you'd have a
very hard time spotting the difference between f/16 and f/22 taken with that
lens in real pictures that aren't contrived to show this effect.

Back to Vitaliy's case.  He was using f/14.  Of course he was using a
different lens.  However the original point you objected to, which was that
diffraction effects are unlikely the source of his symptoms, still seems
quite valid.

Also keep in mind the symptoms Vitaliy described.  He said at f/14 there was
"noise" on the picture.  That's the opposite of what diffraction effects
make a picture look like.  Diffraction looks more like a haze.  It's a low
frequency effect, whereas Vitaliy was clearly seeing a high frequency
effect.


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