I have the Canonflex 100mm F2.0 R lens, as well as an AE-1. The lens will fit, and operate, on the camera with no problems. As mentioned by others, you will have to operate the lens in full manual mode, which you do by using the secondary depth-of-field aperture ring located directly behind the main aperture ring. The lens is a quite good, especially wide-open. I hear it uses the same optics as the highly-regarded Canon 100/2.0 rangefinder lens. For what it's worth, I use the 100/2.0 R on my old F-1 a lot and rarely on the AE-1. The AE-1 just isn't my cup of tea (got it free from a friend).