I am considering buying a second hand Canon 50mm. 1.4 and am wondering what are the main things to look at when checking out the equipment. I am thinking since there is no zoom that simplifies things a little. Would I just make sure it focusses properly, has no mould/dirt/scratches, take a few pics and enlarge on my viewfinder to find any hidden problems? Do you insist on downloading the pics and checking properly on the pc? Would love to get some advice/input from you guys! Cheers.