I have a T3i and have recently noticed when taking a picture with my 50mm ef 1.8 lens it shows crop lines in camera and I don't remember making any changes. All my pictures seem to be square cropped and I can't figure out how to change it. I haven't used the lens very much but I never remembered seeing this initially. I was wondering if this is fixed in the lens or if I may have changed something by accident.
You don't even need to download it if you have access to the internet:
That is what I use to answer these questions. I do not have a copy of every canon manual!