Mounts

• R-Mount - really old thing, started to be used in 1959
• FL-Mount - first really popular manual lenses mount, started at 1964.
• FD-Mount - most popular old Canon manual mount, used since 1971. Compatible with FL lenses.
• EF-Mount - completely new mount, focusing and aperture are controlled by lenses themselfs.
• EF-S Mount - Lenses made for APS-C sensors, can not be used on old EF bodies.
• EF-M Mount - Mirrorless mount used only in Canon M cameras.

More General

• L - Abbreviation for premium lenses.
• I, II, etc - indicate lens generation, usually improved and more advanced lenses have higher number.

Auto Focus related

• AFD - Arc-Form Drive, slowest and noisiest drive. No manual focus override. Bad for video.
• MM - Micro motor, smaller focus drive, also noisy and without focus override. Bad for video.
• STM - Stepper Motor, good for slow focus changes, quite silent, good for video.
• USM - Ultrasonic Motor, fast for still photos focusing, almost silent. Not very good for video.
• Nano USM - latest version of ultrasonic motor, made to be almost silent and good for video.

Stabilization

• IS - Optical Image stabilization, in fact can differ from year to year and lens to lens.
• IS II - Sometimes used to indicate advanced stabilization for newer lens.

Special Lenses

• PZ - Lens with power zoom. Such lenses are made for video work mostly.
• Macro - Lens that have small minimal focusing distance and flat focusing plane.
• Compact Macro - Smaller macro lens that can not reach usual 1:1 macro dimensions, usually 1:2 only.
• MP-E - Ultra Macro lens, like 5:1.
• TS-E - Abbreviation for tilt-shift lenses.

Optical Construction

• SSC - Canon brand of good elements coating. Used only on old glass, now it comes by default.
• DO - Lens with at least one Diffractive Optics element.
• Softfocus - Lens with element making picture dream like.

We have separate page for Canon FD - Canon FD Lenses FAQ

Feel free to contact us if you want to add info for new Canon EF.