Canon Lens Acronyms and What They Mean
If you’ve ever been Canon lens shopping, you’ve probably had to take a minute (or five) to figure out what the name of the lens actually means. With a string of seemingly random letters and numbers, these abbreviations have baffled photographers, beginners, and some professionals alike, for as long as they have been around.
So, instead of hiring a cryptographer to crack these complex codes, here is an easy break-down list of Canon’s lens acronyms and what they mean.
Canon Lens Mount Systems
RF
The RF mount is Canon’s newest lens mount that was launched in September 2018. It was developed to work with Canon’s latest full-frame mirrorless cameras. On account of the shorter flange depth (distance between the lens mount and film/sensor plane), the RF mount has opened the doors for several new lens designs. It has also made smaller and lighter lenses a possibility. If you are looking to use EF lenses, Canon also released three EF to RF adapters. These allow several EF lenses to work with the EOS R mirrorless camera.
EF
Introduced in 1987, the EF mount is the standard Canon DSLR mount today. The lenses marked with EF are compatible with an EOS camera, both digital and film. This means that it will work with full-frame digital sensors, crop sensor cameras, and EOS film cameras.
Unlike its predecessor, the FD mount, this mount was developed to allow for the design of autofocus lenses.
EF-S
The -S in EF-S stands for ‘small image circle.’ These lenses were, thus, designed for cameras with a smaller image circle – the APS-C sensors to be specific.
Though EF lenses can be used on an APS-C camera, a lot of the lens tends to be wasted on the crop body. As a solution to this problem, the cheaper and lighter EF-S mount was introduced. Unlike the EF lenses, however, these lenses cannot be used with a full-frame body. They are also more suited to beginners who start with crop cameras.
EF-M
This new lens format was designed specifically for the Canon EOS M mirrorless camera system. It can also cover the APS-C sensor due to its smaller opening. Lenses marked EF or EF-S can be mounted on an EF-M mount by using an adapter. However, EF-M lenses cannot work with an EF mount.
FD
Appearing way back in 1971 on the Canon F-1, this is the old manual focus Canon lens that was used up until 1987. Since the introduction of EOS mounts and lenses that allowed for autofocus, the Canon FD was discontinued. It is still, however, used by certain film photography enthusiasts.
FDn
This is a new and improved follow-up to FD. The only difference here is that these lens mounts all came with SSC on the lens elements.
FL
Introduced in 1964, the FL mount is almost the same. Except that it does not possess the ability to meter with a wide aperture.
Canon Lens Class and Lens Type
I, II, III
These roman numeral markings on your lens signify the lens’ generation. They are essentially the upgraded version or the revision number. Lenses marked III are newer than those marked II. These indications give the user a way to find a newer or older model of the same lens.
For instance, the Canon EF 600mm F4 L IS III USM, III is the third version of the lens with better optics, tech, etc. than its previous versions.
L
Singled out by a prominent red ring in front, the L lenses represent Canon’s top-of-the-line lenses. These feature some of the most advanced tech and high-quality optical formulae. The L stands for ‘Luxury’, and these lenses live up to Canon’s highest standard.
The collection includes a vast range of lenses – from super-telephoto prime lenses to a super-wide 8-15mm f/4 L Fisheye Zoom. All of these lenses feature Ultrasonic motors, and most of them are also weather-sealed.
As the epitome of professional-grade lenses, the L series stands out for its fast focussing, durability, and price (which is worth every penny).
DO
This stands for Diffractive Optics (DO) lenses. Marked by a green ring around the lens barrel, are built to the same standards as the L series. The diffractive optical technology uses special glass elements to bend more light than regular glass.
This allows for the usage of much smaller glass elements within the lens. As a result, the lens is smaller and lighter than other lenses built with a more standard optical design.
Macro
Lenses of this kind are designed specifically for close-up photography. This is because they focus down to relatively shorter distances and also allow for a 1:1 magnification.
The 100mm f/2.8 L IS Macro lens from Canon is one of the sharpest lenses that they have. Some Canon lenses also include a ‘Macro Mode.’ Though it is not the same as a 1:1 magnification, this comes fairly close to the necessary macro magnification.
Compact Macro
Much like the name suggests, a compact macro lens is smaller than other macro lenses, making it perfect for travel use. Despite its short minimum focus distance (MFD) which allows for close-up work, this lens has a magnification of 0.5.
The EF 50mm f/2.5 Compact Macro is currently the only compact macro lens. There is, however, a converter called the Canon Life-Size Converter EF for this lens. This increases the lens’s working distance and also enables 1:1 magnification.
TS-E
These are tilt-shift lenses – manual focus lenses with tilt and shift capabilities. They allow you to adjust the angle of the plane of focus in relation to the camera’s sensor. They also allow photographers to change the perspective.
Generally speaking, the plane of focus tends to be parallel to the sensor. With a TS-E lens, however, you can position it at any angle from the normal parallel to perpendicular. These lenses are great for creative portraits, landscapes and are especially loved by architectural photographers for their shift functionality.
MP-E
The abbreviation MP-E signifies extremely high magnification optics. From anywhere between 1:1 to 5:1, this lens can achieve incredible magnification.
You need to look for where the standard macro lens reaches its limit. This is where this lens begins to focus on the magnification. This makes the MP-E lens a unique device allowing for ‘super macro’ photos. As the lens does not feature a focus ring, photographers must move the lens physically in order to focus.
Furthermore, the lens has a shallow depth of field and thus requires a focusing rail. As of now, the Canon MP-E 62mm f/2.8 1-5x Macro lens is the only Canon lens of its kind.
CN-E
Canon’s line of cinema-specific lenses, available in a distinct red and black, carry the CN-E mark. These lenses are manual focus lenses and also have a manual aperture control ring. A part of the L series, CN-E lenses are designed for incredible durability and are built to extremely high standards.
SF
Popular in the 70s and 80s (long before the arrival of digital photography) the Softfocus lens was designed to create a dreamy, glowy effect in portraiture and film photography. The Canon 135mm Soft Focus lens, no longer available today, was the only Canon lens with the Softfocus feature.
The lens had an adjustable ring around it that you could turn to give that soft, dreamy look to your images.
Technological Abbreviations
AFD
An acronym for Arc-From Drive, this was Canon’s very first autofocus motor technology and is no longer in the running. The lenses were much noisier and slower to focus than other lenses. They also had no manual override, which meant that you would have to disengage the AF/MF switch to use manual focus.
AL
AL stands for aspherical lens elements. These are designed to improve clarity and sharpness from end to end in an image.
ASC
First introduced in 2014 with the 100-400mm f/4.5-5.6 L IS II, Air Sphere Coating reduces ghosting and flare in backlit situations. This lettering does not appear on the lenses themselves but will appear on the box or packaging of the lens.
BR
BR signifies a newer type of organic lens element called Blue Spectrum Refractive. This element works to reduce chromatic aberration by correcting the blue and purple wavelengths. Currently, the 35mm f/1.4 L II is the only Canon lens with this BR element.
DC
This is an abbreviation Direct Connect. A DC geared motor is a feature of some of the older or more affordable lenses that Canon has to offer. Lenses with a DC motor tend to be slower to focus and noisier than USM or Micro USM models. They also do not offer a full-time manual focusing feature.
DS
DS is the acronym for Defocus Smoothing, which made its first appearance in 2019 on the RF 85mm f/1.2 DS. DS is, in essence, Canon’s version of a lens with a built-in apodization filter – a circular graduated neutral filter. This filter is located behind the lens elements. It helps to smooth out out-of-focus areas in an image, bokeh balls in particular.
FP
This represents a focus preset that allows you to return to a preset focus distance instantly. This is a feature of some super long telephotos.
FR
FR stands for Filter Rotation. If the filter ring placed in front of the lens rotates as you focus the lens, it will have a drastic effect on the image particularly when using a polarizing or graduated filter,
FS
Focus Range Selection allows you to limit the range of focus in a lens. This comes in handy for long telephoto zooms in order to make them auto-focus faster.
IS
This is a Canon acronym for optical image stabilization. This technology is what helps to stabilize a hand-help camera using gyros that counteract minute movements of the camera. By moving some of the lens’ optical elements, this technology counter shakes and provides much sharper results when a slower shutter speed is used for a static subject.
Micro USM
This autofocus motor is, quite simply, a smaller and cheaper version of the USM design. It is meant for low-end lenses and kit zoom lenses. It is much noisier than USM. With the exception of the 50mm f/1.4, it does not allow for a manual focus override.
MM
With the intention to develop less expensive versions of the AFD motor, Canon created the Micro Motor (MM). This, in fact, turned out to be the least advanced AF motor in use.
This motor is even slower and noisier than the AFD motor and does not permit full-time manual focus override. Only the cheapest Canon lenses use this kind of autofocus motor.
As a general rule, if an autofocus Canon lens does not indicate what kind of AF motor is in use on its barrel, then it is either MM or AFD.
PZ
Short for Power Zoom, this is a dedicated motor that makes it possible to change the focal length of the lens. The 35-80 f/4-5.6 PZ is the only lens from Canon that uses this.
STM
Stepper Motor is a motor that allows for a smoother and quieter focus by minimizing the autofocus vibrations as well as the noise that occurs while video recording. These STM lenses use a focus-by-wire system. This means that the focus ring controls a motor, which then moves the internal lens elements.
SC and SSC
Acronyms for Spectra Coating and Super Spectra Coating, respectively, which made an appearance on Canon lenses at the time of the FD lens. These coatings applied to optical lens elements were meant to increase contrast and decrease any flare and reflections.
While SC was used for cheaper lenses, SSC was meant for the more expensive ones. As the lenses today are coated with complex multi-coats, SSC is no longer in use.
UD
UD stands for ultra-low dispersion glass, which is used to correct chromatic aberration.
USM
This abbreviation is an indicator of a lens being equipped with Canon’s top-of-the-line focusing motor – the ring-type, UltraSonic Motor. USM is used in most of the latest Canon lenses. This motor allows for powerful, fast, and quiet autofocus and permits full-time manual focus override.
Final Thoughts
I hope this guide helped and cleared up any confusion. In today’s world, there is a huge selection of lenses available; understanding these acronyms could be hugely beneficial when trying to determine which one will work best for you.
About the author: Adam Georges is one of the owners of the independently-owned Australian camera and electronic retailer Georges Cameras. Since 1981, Georges and his team have been providing advice on all the major brands and products. Check out Georges CameraTV YouTube channel or visit the camera store’s blog for more educational content about photography.
