01-20-2020, 11:55 AM
(01-20-2020, 11:10 AM)Brightcolours Wrote:(01-20-2020, 08:23 AM)JJ_SO Wrote:(01-20-2020, 06:30 AM)Klaus Wrote: Distortions will not vary between samples in any substantial way.
Of course, there'll be slight variations - lenses aren't digital after all - but there'll be no qualitative difference.
Can you quantify the "non-substantial" way? To me the diff between -1.28%, -1.35% makes 0.07%. I would not call that "substantial". That was my reason to ask for sample variation. Be it that, or variation in measuring method, I still don't believe that distortion is absolutely excluded from any variation. The differences might be very small and neglible, but there's absolutely no reason why this property should not be affected. There are differences in resolution big enough to appear on charts...
Decentered elements impact sharpness, but not things like focal length or distortion. With no decentered elements you see very little difference in sharpness.
Lens elements get made (and always have been made) with a lot of precision, you do not see different focal lengths, different distortion or differences in chromatic aberrations between lens samples unless the geometry has been seriously damaged.
I have no problem to agree on "small differences", I do have a problem agreeing on "no differences". So far no one has ever been so masochistic as to measure the deviations in distortion and chromatic aberrations of several copies of the same lens. This does not have to change.
But the assertion that there is no deviation is questionable. "Those who feel healthy have just never been properly examined".