Canon Lens Abbreviations & Acronyms (A Quick Guide)

Welcome to a guide and list of the Canon lens abbreviations and acronyms. The geeky scientists and engineers at Canon make some great lenses. But it seems to be a common practice for them to use secret codes. What do the EF, STM, RF abbreviations mean? Fear not, let us walk through the common abbreviations, and a short history lesson to help you better understand – Read on!




Time Period Mount System
1930~1950 Leica Screw Mount (LTM).
1959 R Mount.
1964 FL Mount.
1971 FD Mount, FL lenses can be used on FD cameras.
1987 EF Mount, for the EOS camera series. All previous LTM, R, FL, and FD lenses can no longer be used on the EF mount system. But adapters are easily available.
2003 EF-S Mount, an upgraded version of the EF mount. EF-S cameras can use EF lenses, but EF-S lenses cannot be mounted on an older EF camera.
2003~2012 EF-M Mount. An upgraded EF standard for the Canon mirrorless systems. But nope, EF-M doesn’t mount onto the EF-S systems. Not without an adapter again.
2012 PL Mount. Only used on the higher-end Cinema EOS cameras. Yep, these are lenses meant for film production.
2018 RF Mount. Yet another different mount system for the EOS R and EOS RP line of mirrorless cameras.

Yes, Canon has a notorious history of changing its mount systems, with lens compatibility being a huge pain to Canon users.



Canon seems to love over-glorifying its auto-focus motors. I don’t understand a need to do so, but here goes:

  • AFD: Arc-Form Drive. Pioneer generation autofocus motor that is used in the Canon EF lenses. Slower and louder, does not have manual focus override either. Can be a pain sometimes when shooting in low light.
  • MM: Micro Motor. Basically, this is the smaller version of the AFD motor. Similarly, does not have a manual focus override.
  • STM: Stepper Motor. Gradually becoming the “default motor” for the mainstream Canon lenses. Designed to be a little faster than the AFD, and less noisy for video recording.
  • USM: UltraSonic Motor. This is supposedly the top-end focusing motor for the Canon lenses. Fast, quiet, and powerful.
  • Micro USM: The smaller and simpler version of USM. Generally used in the smaller lenses.




Canon calls its stabilization system “optical image stabilization (IS)“. Not that useful when shooting on a sturdy tripod, but good for videos.



  • PZ: Power Zoom, meaning, this lens has a dedicated motor for “auto zooming”. I know, my initial reaction was also “who is so lazy to even turn a ring”? But as things turn out, power zoom is actually a very useful mechanism for taking videos, where you need a smooth zoom transition.
  • Macro: A lens designed to be able to focus very close up to the subject.
  • Compact Macro: Self-explanatory, a compact macro lens.
  • MP-E: Very high magnification lens, up to 5:1. You can call it a microscope.
  • TS-E: Tilt-shift. Read this on Wikipedia if you do not know what tilt-shift is.
  • EXTENDER: This is not quite a lens, but a range extender. In simple terms, something like a magnifying glass.




  • SSC: Super Spectra Coating. Basically, a special lens coating that minimizes reflections and boosts contrast. All modern Canon lenses are multicoated “by default”, so you will only find SSC marked on the older Canon lens.
  • DO: Diffractive Optics. Technicalities aside, lenses with DO have “special glass elements”, which are said to be sharper and lighter than the regular lens. DO lenses are marked by a green band, deemed to be better than the regular Joe, but slightly below the red ring “L” lens (see below).
  • Softfocus: These lenses produce soft images deliberately. Well, it’s all about that retro dreamy creamy effect. No longer popular and these lenses are not produced anymore. If you want that soft effect, just buy a cheap softening filter instead… Or just rub some Vaseline on the UV filter.
  • DS: Defocus smoothing. In layman terms, this lens produces “blurred bokeh balls” and not “sharp circles”.



Canon calls their top of the creme lenses “Luxury (L)”. Very easy to spot, all L lenses come with a signature red ring.



Just like the camera bodies, revised Canon lenses adopt the same Roman numeral version numbers – Mark 1 (I), Mark 2 (II), Mark 3 (III), and so on…




Thank you for reading, and we have come to the end of this short guide. I hope it has helped you to better understand and here are a couple more links that may be useful to you.

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