Canon EF Lens
Canon has two different types of lens mounts. The Canon EF and EF-S lenses make up all of Canon's SLR lenses. While they have many similarities, the differences between the two are important to understand when purchasing a lens for your new Canon SLR camera body. It all depends on the type of Canon camera body that you have. EF lenses will work with all types of Canon camera bodies but EF-S lenses will only work with certain Canon camera bodies.
Definition
Canon EF and EF-S lenses refer to the type of camera the lenses can be mounted to. In 1987, Canon made all its camera mounts universal for all its SLR cameras, both film and digital. EF stands for "electrofocus." They are distinguished by the red dot that helps to align the lens with the camera mount when placing the lens on the camera. EF and EF-S lenses are a bayonet style mount that has electrical contacts that help the lens talk to the camera.
History
Prior to EF and EF-S mount lenses, Canon had FD mount lenses. FD lenses used the camera's motor to mechanically focus the lens. EF and EF-S lenses have a dedicated motor built into the lenses that help focus the lens on the image. This greatly improved the auto focusing on lenses. In 1987, when the EF lenses were introduced they were originally mounted on 35mm SLR cameras. In 2003, Canon introduced their digital SLR line and the beginning of the EF-S lenses. Canon digital SLR camera bodies have a smaller mirror box than 35mm film cameras, therefore there was a need to create lenses that would work with them. They are also known as "crop body" cameras. Canon has also created a line of "full frame" digital SLR camera bodies that are equivalent to a 35mm film frame.
EF
EF lenses fit all Canon EOS camera bodies from "crop body" digital SLRs to full frame SLRs. They will work with the 35mm line of cameras as well as the digital SLR cameras. The EF series of lenses includes Canon's professional line of "L" series lenses which are recognized by the red line around the lens. Canon EF lenses are recognized by their red dot on the lens. EF lenses have many controls on the lens from the auto focus to manual focus switch, focusing ring and zoom ring.
EF-S
EF-S lenses are designed to accommodate Canon's line of "crop body" digital SLR cameras. They are distinguished by the white square on the lens instead of the signature red dot of the EF lenses. EF-S stands for short back focus. The lens sits back into the camera body more then an EF lens. EF-S lenses range from inexpensive to mid-range in price and are paired with Canon's entry level to mid-range digital SLR camera bodies. They are not compatible with "full frame" digital SLR camera bodies or 35mm film camera bodies.
Tags: camera bodies, EF-S lenses, Canon camera, digital camera, digital camera bodies