It's obviously that time of year when measuring lens performance becomes so popular. I just saw the thread about the Tamron 17-50 vs the Canon 50 F1.8 and, spookily, today I shot some test images to compare my Canon 17-85 and my Canon 50 F1.8.
I was looking for focus/sharpness comparisons and shot an A4 newsletter with pretty sharp looking print. All shots were handheld and shot at F5.6 to make the comparison as equal as I could. I took three shots with the 50mm, then three shots with the 17-85 at 50mm, composing and focusing fresh each time.
I then also took shots with the 17-85 at 17mm, 24mm, 35mm, 50mm (again), 70mm and 85mm. As I zoomed with the lens I also zoomed with my feet to keep the image roughly the same size in each shot.
I then took 100% crops from the centre and also 100% crops from the bottom centre edge as well. Apart from the first shot with the 50mm looking dodgy, I think due to camera shake, I'm pretty hard pressed to spot the difference between any of the remaining shots. Sure there are differences but that's viewed at 100%. In normal viewing there is really nothing to choose between them.
Centre crop results are here....
http://picasaweb.google.co.uk …formanceComparedTo50mmF18
Bottom edge crop results are here....
http://picasaweb.google.co.uk …formanceComparedTo50mmF18
Full EXIF data is included in the cropped photos.
I know the 17-85 comes in for a lot of criticism (not from me!), whereas the 50 F1.8 comes in for lots of praise. I know it barrels at 17mm and vignettes a bit but I have never had a problem with CA on my copy. But judged on these results there is little to fault in the 17-85 as far as sharpness is concerned.
