Question: What is the difference between EF and EF-S cameras and lenses?
Answer: EF lenses can be used with either "full frame" or "APS-C" DSLR cameras. EF-S lenses can be only with "APS-C" DSLR cameras.
Each Canon DSLR camera is equipped with either a 24mm x 36mm ("full frame") or 22.2mm x 14.8mm ("APS-C") sensor. Cinema cameras using the EF mount (Canon EOS Cinema cameras, Arri Amira, Arri Alexa Mini, RED Digital Cinema cameras, Blackmagic Design cameras, etc.) have various sensor sizes, depending on the model of cinema cameras.
When using EF or EF-S lenses with any camera other than a Canon DSLR, it is important to check whether the lens is compatible with the particular camera.
EF lenses have an image circle that covers the 24mm x 36mm sensor, whereas EF-S lenses have an image circle that will cover the 22.2mm x 14.8mm sensor, but will NOT cover the entire 24mm x 36mm sensor. Further, EF-S lenses cannot be physically be mounted on EF DSLR cameras, as there is the potential for either the camera or the lens to be damaged.
If you have any questions about camera and lens compatibility, Hot Rod Cameras would be glad to help you find answers.