For anyone who knows anything about photography.....I currently have a Canon Rebel Ti 35mm body with the regular 90mm lens plus a 300mm zoom. I am thinking of upgrading to a DSLR but have heard that film lenses won't work on digital bodies? Is this true and why not? I would much rather spend a few hundred on a new body rather than a few thousand on a new body and new lenses. Any info would be helpful!