What does canon lens ef mean?

EF: Electronic Focus, the bayonet name of Canon EOS camera, and also the serial name of EOS original lens. ?

Ef is Canon's EF lens, and Canon basically follows a principle in the use of motor for EF series lenses: it uses annular USM and AFD as high-end collocation for high-end "L" lenses and medium-end lenses, and micro USM and MM motors as low-end collocation for low-end lenses.

EF-S: Canon's lens specially designed for SLR digital cameras, which is characterized by allowing the rear lens group to extend backward for a certain distance.

Extended data:

EF lens names consist of many numbers and letters. All values and symbols have their own meanings. Knowing these meanings can give you a general understanding of the characteristics of the lens.

The lens name can be roughly divided into four parts: ① lens type, ② focal length, ③ maximum aperture and ④ lens characteristics. In addition, the arrangement order is also regular. Generally, lenses are arranged in the order of ①-④. If there are many symbols representing lens characteristics, such as the lens name of EF 70-200mm f/2.8L is II USM, then these symbols will be arranged at the end in turn.

References:

EF lens basics-Canon official website