Yesterday the PhotoSoc had a great lecture/demo on film (link is members only, I’m afraid), and someone asked about the possibility of using Canon EF-S lenses (you know, the ones that are made for the APS-C digital bodies) on a film (ie full frame) camera. I claimed it was not possible, so did some digging this morning to double-check.
As it turns out, quite a few people had been asking the same question, so quite a few had also provided the answers. I like this one – could not have said it better myself. Wikipedia also talks about this in the EF-S lens page (check the compatibility section). Basically it boils down to: you can, but only by modifying the lens rear. I would not bother – you’d end up with some horrible vignetting anyway. But I can see why some would be interested to try – you can get some crazy short focal lengths and ‘interesting’ effects.