Softness on the edge

Started Feb 22, 2021 | Questions thread
Andy01 Veteran Member • Posts: 4,849
Re: comparing the 16-35 and 17-40

I would have expected the corners to be less soft (softer than the rest) at f20. I mean - it is f20 for goodness sakes

The point is that people buy this lens because it is a cheap constant f4 L series zoom lens only to find that the performance is really quite poor on FF (edges & corners at anything close to f4.

Sure it can be stopped down to f11 and crop out the soft edges & corners, but then what is the point of buying a 17mm f4 zoom if it cannot be used (and achieve reasonable IQ) at f4 and 17mm ?

Many argue that in many cases the edges or corners are not important, and sometimes this is true, but not always.

Many will say that they want the lens for daytime landscape or real estate on a tripod, so f4 doesn't matter because they use f8 or f11, and this is probably true as well, but how many people buy a lens exclusively for those purposes and never to use as a walk around WA when on vacation for example.

Personally if I buy a lens (especially an L series lens) I expect it to perform reasonably well at all focal lengths and apertures - there will always be some that are better than others, but I will never buy a 17-40mm f4 that I can only really get decent frame wide performance if I use f11 and cop out the outer 10% of the frame on all sides - what is the point ?

Look at this - the difference between 17-40L f4 and 16-35L f4 at f4 and widest setting is like night and day to me - perhaps you got an exceptional copy of the 17-40L and your friend got the world's worst copy of the 16-35L ?


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