I know that my old lenses from my Canon film SLR will fit on my new digital SlR and yes they do work but being new to Digital SLR's and a rank amateur, how do I actually know if they are satisfactory/still good for the job. Should I get them looked at? Should I just practise and see? I don't know if my own judgement is good enough. My old Eos 630 was used with Canon EF 28-70 and Sigma 70-210. My current camera is Canon 50D. I was going to buy new lenses for a course I will be attending.