>> 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. =A0Even this test showed little
> degradation at f/16.

That's not that little degradation: 200 vs 165

> If I remember right, you were claiming problems at f/11.

It was Vitaliy, the OP, who talked about f/14,you who said that
diffraction should not be a problem at f/14 and me who said that
diffraction could be a problem at f/14.


> 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.

Of course, I got no experience in the area (and I don't plan to get
any), but even I would definitely spot the difference visually between
MTF 200 at f/8 and MTF 150 at f/22. The link was:
http://www.photozone.de/canon-eos/167-canon-ef-100mm-f28-usm-macro-test-rep=
ort--review?start=3D1

And for Russell's example  "Canon PowerShot G6 (compact camera) begins
to show its effects at only about f/4.0-5.6", the difference would be
even greater. Who knows, perhaps Vitaliy owns exactly PowerShot G6?


> Back to Vitaliy's case. =A0He was using f/14. =A0Of course he was
> using a different lens. =A0However 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. =A0He said
> at f/14 there was "noise" on the picture. =A0That's the opposite of
> what diffraction effects make a picture look like.

Vitaliy said: "it comes out sort of blurry/noisy", not just "noisy".

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