Slide Copiers for EF bodies
sam, you can use a bellows fl (there was at least one other model too) with the slide duplicator attachment. you'll also need an eos to fd converter. i have a cheap generic model that i think i got from b & h, it works fine. though you can find better ones for more bucks. you can use the tremendous fd 50mm macro lens that was designed for that bellows, or a regular 50 on a reversing ring (to obtain flat field). another option is to find a way to mount an enlarging lens, i've done that with some odds and ends adapter rings i've found at camera shows. there are also a couple of funky wide angle macro lenses canon made for the bellows, you wouldn't want to use them for slide copying though. this would all have to be found used.
novaflex currently makes an eos bellows. and also a lens reversing adapter that retains metering and aperture and auto focus functions. it all costs a fortune though!
i don't actually use my bellows for slide copying, i use it for macro shots. but i use that same eos to fd adapter with a durst chroma pro slide copier which has dial in dichroic filters just like a color enlarging head so you can make color corrections/adjustments. (speaking of which if you have a color enlarger that can be adapted for slide copying as well, at least my super chromega c can. i know others can as well) but it doesn't have a built in meter. then there is the bessler dual mode slide copier (or some such name) this has a sophisticated built in meter and density/contrast control function, but no filters like the chroma pro has (it also costs way more). i think the bessler's are still made but the durst is not. (mine was a steal used at a camera store)
you can also get one of those cheap tube type slide copiers which is probably the cheapest and easiest method but the least flexible.
two more methods in a pinch would be to use a copy stand and your slide on a masked off light box. or if worse came to worst just a camera on a tripod lined up as best you can with your slide on a light box on the floor or rigged to a wall somehow
once you get your set up figured out then you need to deal with what film to use and how to expose it. that's another can of worms. you don't say whether you want to make slide dupes or negs. btw, i mentioned built in meters in the bessler unit, but if you use any of the other methods you can use the camera meter. just set it on manual and set the f stop to f1.0, it seems to work pretty well but you can bracket for safety or better yet do some testing to find exposure times that work with various density slides (or power setting/distances that work with flash if you're using a bellows or tube). of course none of the exposure stuff is a worry if you go the novaflex rout either
well those are most of the options i can think of, recommendations? the bellows is nice, allows for cropping, and has the added function of being a great macro set up. the durst and bessler units are great precision machines totally designed for the task, but serve no other function and are big, bulky, heavy and possibly very expensive depending on your luck. all the other methods are compromises
phew! well that's my few dollars worth