It will fit all the standard canon stuff, including EOS. I have one, works fine on my 1VHS, A2, 650, and older manual canon bodies too. Also fits most other 35mm gear - they most all had a fairly standard eyepiece frame size since way back.
Ok, just figured out my EF, Eos 630 and ae-1 have the same shaped eyepiece frame. They dont use the same cup designs, so I assumes they made them completely incompatible.