PBase

Can someone explain to me why my old canon EOS film lenses never worked as well as lenses made for digital?
I have replaced the old ones now but I actually never knew why these older electronic focusing lenses were not that hot.

As far as I know its about the reflective area of a sensor. Film will absorb and not reflect, a sensor will reflect, thus causing a much more complex lightproblem. Lenses made for digital cameras have extra coatings to suppres reflections coming from the sensor.

In addition, the surface of a CCD or CMOS sensor is not flat, so light coming in at an angle can cause shadowing of the actual photosensitive site by the wiring and other components located at a higher elevation on older sensors without integrated microlenses. That leads to additional falloff at the edges and corners, which made-for-digital lenses counteract by having the light arrive as close to perpendicular as possible across the entire area of the sensor.

Also all of the electronics in camera and lens have been improved since the film only days (which was a long time ago in technology terms). If you put one of the newer lenses on a film camera it would also perform better.