Canon EOS EF Lenses from film cameras can be used in Canon digital cameras which use EF-S lenses… sort of. They are not 100% interchangeable. A couple bid deal issues which must be considered.
- EF lenses from Canon film cameras will work on Canon digital cameras that use EF-S lenses, the reverse however is not the case. The reason is that EF-S lenses project further into the camera body, and as such they will not fit, and may even damage the mirror mechanism on film cameras.
- Digital camera sensors are for the most part smaller than 35mm film. The exception being cameras with full frame sensors, such as the Canon 1Ds etc. As a result of this, the lens effective focal length changes, typically by a factor of 1.6. As such a 35-80mm zoom lens becomes a 56-128mm.
- There may be other factors as time passes, it is always best to check with a competent camera guy before buying something only to be disappointed, or worse, damage your unit.