Canon EOS is an autofocus single-lens reflex camera (SLR) and mirrorless camera series produced by Canon Inc. Introduced in 1987 with the Canon EOS 650, all EOS cameras used 35 mm film until October 1996 when the EOS IX was released using the new and short-lived APS film. In 2000, the D30 was announced, as the first digital SLR designed and produced entirely by Canon. Since 2005, all newly announced EOS cameras have used digital image sensors rather than film. The EOS line is still in production as Canon's current digital SLR (DSLR) range, and, with the 2012 introduction of the Canon EOS M, Canon's mirrorless interchangeable-lens camera (MILC) system. In 2018 the system was further extended with the introduction of the EOS R camera, Canon's first full frame mirrorless interchangeable lens system.

An autofocus optical system uses a sensor, a control system and a motor to focus on an automatically- or manually-selected point or area. An electronic rangefinder has a display instead of the motor; the adjustment of the optical system has to be done manually until indication. Autofocus methods are distinguished as active, passive or hybrid types.