Ensuring the lens is fine

What are some test I can do to make sure my lens focuses correctly and it is not a bad copy? Would I be able to send my lens to Canon and request a replacement? I bought it last fall, so it it under warranty.

You would not be able to get a replacement. They would calibrate your lens to your camera (which you would also have to send them). Replacements only fall under the return policy of the store which you purchased from.

If Canon can't fix the focusing issue after, I believe, three times, then you'd be able to get a replacement.

And the best way to make sure it focuses correctly, go out and shoot. If it focuses, then it works. Otherwise, you could sit at home doing all those scientific tests lining up batteries and pieces of paper. If you've purchased the lens last fall, you should know if it focuses properly or not. Have your pictures come out in focus? If so, then it's not a bad copy.

can canon fix a soft copy? or just calibrate focusing to your camera?

TheAnt wrote in post #12640677
...And the best way to make sure it focuses correctly, go out and shoot. If it focuses, then it works. Otherwise, you could sit at home doing all those scientific tests lining up batteries and pieces of paper. If you've purchased the lens last fall, you should know if it focuses properly or not. Have your pictures come out in focus? If so, then it's not a bad copy.

Big +1. If your pictures are in focus, don't look for a problem where there isn't one.