Can you share canon lenses with all canon cameras?

The short answer is "Depends" The long answer is: From 1971 to 1987, Canon SLR bodies and lenses used the Canon FD mount. In 1987, Canon introuduced the EOS SLR system. All EOS cameras use Canon EF (auto focus) lenses. They can also use independently made lenses with EOS type camera mounts. Canon FD and EF lenses have completely different mounting connections and are not compatible with each other's camera bodies. All Canon DSLR (digital single lens reflex) cameras can use all Canon EF (or independent manufacturer equivalent) lenses made for film or digital cameras. Most Canon DSLR's have an APS-C sensor that measures 22.2 x 14.8mm. (This is smaller than the 36 x 24mm image size on 35mm film.) In 2003, Canon introduced EF-S lenses that were optimized for the APS-C sensor size. The EF-S lenses will only fit on Canon 20D, 30D, 40D, and 50D cameras (as of 2008) and all Canon Digital Rebel cameras.