http://www.adammillerrealtor.com/camera-lenses-canon-ef/
When talking Canon & EF-S lenses…does all Canon EF compatible cameras use EF-S lenses?
or is the “S” a meaning for something else?
ok…but Why does the Canon 7D have mountings for both EF and EF-S but it has a APS-C sensor? will that not be a problem and result in undesired Vignetting?
‘S’ stands for “Short Back Focus”. They are designed for optimum performance when used on cameras with the small APS-C sensors like the 7D and 50D. (Do not attempt to mount an EF-S lens on a FF camera. The mirror can be damaged.)
* EF lenses can be used on FF and APS-C EOS cameras.
* EF-S are used only on APS-C EOS Cameras.
Addendum:
“Why does the Canon 7D…will that not be a problem and result in undesired Vignetting?”
Not at all. The image circle of an EF-S lens is a perfect match to the APS-C sensor in the 7D. No vignetting if you use a EF or EF-S lens on the 7D.
(Of course the larger image circle of the EF lens will not cause vignetting on the 7D. That’s a given.)
Canon EF 50mm f/1.8 II Camera Lens for Sale (Cheap)