Do You Check Lens Sharpness Before You Buy?

I'm wondering if in people's real work experience, before you buy a lens do you check several copies and find one that's sharpest on your body? Can you tell the difference between each copy? I not done this to date and not been unhappy with the sharpness of what I have, but have I just been lucky?

Good question. I'm sure some people do check carefully before they buy, this is especially the case in countries like China as there is no return policy whatsoever... However, on the other side of the globe, personally I don't have any concern about my lens being not as sharp as expected. I usually trust Canon or whatever it is, and I'm also the one to keep getting good copies (actually everybody should). If you search online I think there are numbers of comparison between copies and there are indeed people saying that some lens is not very consistent in optical quality. The bottom line is that we can always take our lens back to the shop if we're not satisfied, and I think doing tests among copies at the store will not be very unwelcome either...