Canon 7D Instruction Manual - Accessory

Canon’s EF-S system was announced in 2003 as the crop sensor variant of the standard EF mount. EF-S lenses are designed for DSLR cameras with APS-C sized sensors. The S in EF-S even stands for small!

EF lenses intended for full frame cameras can be mounted on EF-S bodies, but EF-S lenses cannot be mounted on EF bodies.