Ok I've seen a few images around here where the exif says ... f=22 or similar.

diffraction!

There's usually no issue and the images have appeared fine, but(!!) I've been seeing a lot of lens tests/comparisons where the tester has noted things like "diffraction causes problems from f/16, as is to be expected..." or words to that effect.

It appears to afflict certain cameras worse than others, they all do it, but to what degree?

As I've read many lens tests proclaim it to be a problem, I tend to use a min f/11-13(f/16 on some occasions) for any landscapes where there's excessive light... many at f/8.

I'm wondering if any folks here are aware of this 'problem'?

I finally found a technical link that many folks can "visually understand" (meaning I finally see what they're on about ).

THE TECHNICAL LINK!

the site is interactive, so you can see what diffraction does to an image, and explains technically what's happening within you camera(the sensor).

OK here's the catch! The sharper the lens the WORSE the diffraction appears!!

It actually makes sense really, if your lens is sharp as a tack(hey Dowden, you still got that 70-200? ) then you will notice any blurry abberation more than you would if the lens was already softish