How can I tell if my Canon lenses will fit a digital camera?

I have a Canon Elan 7 and was planning on purchasing the Canon 50D. I have a few Canon lenses to go with my camera and did not know if they would be compatible with the digital camera I was getting. How can I tell if I can switch the lenses between digital and film? So I know if I need to buy a lens to go with the camera or not.

Thanks!

I am open to any other feedback about the camera too.

Yes they are all compatible. The only Canon lenses that are not compatible with the new digitals are the manual focus FD mount made prior to the advent of auto focus. These lenses will all have been made prior to 1987.

The new digital only lenses which are marked EFs are not compatible with your Elan or the full frame digitals like the 5D and above. There really is no reason to have more than 1 or 2 of these though. The EFs 10-22mm in my opinion is the only EFs lens that you need to have. This is because there isn't a EF lens that is wide enough on the crop sensor or APS-C sized sensor of the low to mid range Canon cameras. The only other EFs lens you may want would be the 18-55mm lens that comes with the Rebel cameras. There are however better EF models that cover this range like the EF 17-40 F4L for example.

Bottom line though is they will work just fine.