Might be a dupplicate, but I don't think it is...
Looking here : Comparaison of a Canon 1200D and a Nikon 3100
I've seen that the Canon 1200D has a mount type called "Canon EF-S".
I know that you cannot mount EF-S lens on a full frame, but I never quite realized that camera had their mount specification as well (which is logical but still...)
Anyway, does it mean that you cannot mount an EF lens on this kind of entry level DSLR ?
No. All Canon cameras that accept EF-S lenses are also 100% compatible with EF lenses. A camera having an EF-S mount simply means that you can also attach EF-S lenses to it - the limiting factor is the camera, not the lens, as the rear element of EF-S lenses may extend so deep into the mirror box as to obstruct the movement of the mirror of an EF mount camera.
Many 3rd-party lenses designed for a crop sensor are mechanically compatible with EF mount cameras, though, it's just that you get severe vignetting (usually completely black corners) due to the smaller image circle.
