FEChariot wrote in post #16998622
What lens is in each of those? The second looks decentered or something. Was the sensor parallel to the wall?
16-35 f4 vs 17-40. Yup. I checked all corners for similarity and the center for focus. Obviously mounted both lenses to the same camera on a fixed tripod, so no change or orientation. I made sure the center was the same (it was, the center sharpness is very similar between the lenses) and then chose a representative extreme corner. It is also the extreme corner - in fact you can see even across the 800px of all the images the 17-40 sharpness changes a lot. If you look at the top right of the 100% crops (I guess I should have mentioned that - I assumed everyone would realize) then the sharpness difference between the lenses is not as dramatic. It's really the extreme corner drop-off in sharpness of the 17-40 that the 16-35 f4 addresses, particularly at the wider apertures where the corner sharpness of the 17-40 degrades dramatically.
I don't know about the digital picture test charts, but my 17-40 looks like other examples I have seen. Perhaps their 'corner' is not the extreme corner, IDK. BUT, the thing is in 'real world' shooting at f8 or f11 you run into DOF issues anyway which make the comparisons less stark. Plus you can sharpen the corners of the 17-40 a bit more (these are all unsharpened) so they will look even more similar after processing. So I do also agree with the points made by others. The 17-40 is still a good landscape lens stopped down, maybe needs a bit more care in sharpening the image and I'm guessing the 16-35 II is also. But I have never used a 16-35 II, so I'm not making any comments about the new lens compared to that lens.
Edit: I guess thinking about it it doesn't 'prove' my 17-40 is not slightly decentered in the horizontal or vertical planes. I probably wouldn't have noticed since I nearly always use it stopped down to f11 or beyond.