Like most lens manufacturers, Canon uses codes in their lens names to identify key features and technologies of the lens.
Some designate mount types, impacting the compatibility of the lens with certain types of Canon cameras. Others designate technologies such as lens coatings that improve the optical performance of the lens. And others signify the type of lens and its suitability for particular purposes.
Canon has been making camera lenses for a long time, and over the years, they’ve used many codes. Once you know how to read them, they can be very useful. But they can also be confusing.
So here’s a breakdown of many of the codes Canon has used over the years on their camera lenses. I’ve grouped them by the type of information they convey.
Canon Lens Codes for Mount Types
Codes in this category help identify which lenses are compatible with which types of Canon cameras.
- RF – Stands for “R-Focus,” designed specifically for Canon’s R-series mirrorless cameras. These lenses use a shorter flange distance compared to EF and EF-S lenses, allowing for a more compact design and enhanced image quality. RF lenses are also known for their custom control ring, which can be programmed for various functions such as aperture or ISO control.
- EF – Stands for “Electro-Focus,” a lens mount designed for all of Canon’s EOS cameras, including full-frame digital, APS-C digital, and 35mm film cameras. Introduced in 1987, EF lenses use electronic connections between the camera and the lens for autofocus, aperture control, and image stabilization. This system allows for faster and more accurate focus, as well as greater compatibility across a range of camera bodies. This has been Canon’s workhorse lens category for years.
- EF-S – Designed specifically for EOS cameras with APS-C sensors, these lenses provide a smaller image circle that matches the smaller sensor size, offering a more compact and lightweight design. Due to the reduced image circle, using an EF-S lens on a full-frame or film EOS camera may cause vignetting or, in some cases, damage the camera’s mirror.
- EF-M – Designed for Canon’s EOS M-series compact mirrorless cameras, these lenses have a smaller form factor and shorter flange distance than EF and EF-S lenses. EF-M lenses are tailored for the smaller APS-C sensor used in EOS M cameras, offering a balance between portability and image quality for photographers seeking a lightweight and versatile system. They cannot be used on other EF-mount cameras.
- FD – Canon’s older manual-focus lens mount, which preceded the EF mount. FD lenses use a breech-lock mechanism to secure the lens to the camera body, allowing for smooth and precise manual focus. With the introduction of the EOS system and EF mount, FD lenses were discontinued and are now mainly used by enthusiasts and collectors.
Canon Lens Codes for Autofocus Motors
Canon has used several generations of autofocus motors in their lenses over the years, making them better and better. The most common that you’ll come across in today’s lenses is USM.
- USM – Stands for “UltraSonic Motor,” Canon’s main focusing motor technology. USM lenses provide fast, quiet, and accurate autofocus performance, with the added benefit of full-time manual focus override for precise adjustments.
- Micro USM – A variation of the UltraSonic Motor, Micro USM is used in some smaller and lighter lenses due to its more compact design. While not as fast or quiet as a regular USM, Micro USM still offers efficient and accurate autofocus performance.
- AFD – Stands for “Arc-Form Drive,” a predecessor to Canon’s USM technology. AFD lenses use a motor that moves the focusing elements in an arc, providing smooth and accurate autofocus. While not as fast or quiet as USM, AFD lenses still offer reliable performance.
- STM – Stands for “Stepping Motor,” a focusing motor technology designed for smooth and near-silent autofocus during video recording. STM lenses are ideal for use in video production or with Canon’s Dual Pixel autofocus system, providing seamless and essentially noise-free autofocus performance.
- NANO USM – This is a newer focusing motor technology that combines the best features of USM and STM motors. NANO USM lenses offer fast, near-silent, and smooth autofocus, making them suitable for both still photography and video recording.
Canon Lens Codes for Lens Coatings
Applying the right kinds of chemical coatings to a lens provides optical benefits, such as reducing stray reflections and/or improving contrast. These days, most modern Canon lenses are multicoated as a standard feature, so these codes have become less common on newer models.
- SSC – Stands for “Super Spectra Coating,” a proprietary lens coating technology used to reduce glare, reflections, and improve contrast in images.
- ASC – Stands for “Air Sphere Coating,” a lens coating technology designed to reduce flare and ghosting, particularly in backlit situations. ASC uses an ultra-low refractive index layer combined with nano-sized air particles to minimize reflections and improve image quality.
- SWC – Stands for “Subwavelength Structure Coating,” a lens coating technology that reduces ghosting and flare caused by strong light sources. SWC uses microscopic cone-shaped structures on the lens surface to minimize reflections, providing improved image quality in challenging lighting conditions.
Canon Lens Codes for Optical Technologies
Some lenses feature notable technology that the designers (and marketers) consider worth highlighting in the name of the lens and may well influence a buyer’s decision (and the price). An important example is newer lenses that feature lens optical stabilization.
- IS – Stands for “Image Stabilizer,” a technology that provides optical image stabilization within the lens, compensating for camera shake during handheld shooting. This feature helps to maintain sharp images at slower shutter speeds, providing more flexibility in various shooting conditions. Note that this refers specifically to a feature built into the lens; some cameras also feature in-camera optical stabilization.
- L – Stands for “Luxury,” designating Canon’s high-end lenses designed for professional use. L-series lenses feature superior optical performance, build quality, and weather sealing. They are easily identified by a red ring around the barrel of the lens.
- UD / Super UD – Stands for “Ultra-low Dispersion” and “Super Ultra-low Dispersion” elements found in some Canon lenses. These special glass elements help to minimize chromatic aberrations, providing sharper images with more accurate colors.
- Fluorite – Some Canon lenses use synthetic fluorite elements to achieve superior correction of chromatic aberrations and better overall image quality. Fluorite elements are more expensive to produce but offer improved optical performance in high-end lenses.
- BR – Stands for “Blue Spectrum Refractive,” an optical technology used in some high-end Canon lenses to minimize chromatic aberrations. BR lenses use a special organic material that refracts blue light more effectively, reducing color fringing and improving overall image quality.
- DO – Stands for Diffractive Optics. This technology allows Canon to create lenses that are more compact and lightweight while maintaining high optical performance. By incorporating diffractive optical elements, Canon can minimize chromatic aberrations, reduce overall lens size, and maintain image quality. DO lenses are especially beneficial for telephoto lenses, where size and weight are crucial factors.
- PZ – Stands for “Power Zoom.” This specific version is only found in a handful of Canon lenses. Power Zoom lenses offer smooth, variable-speed zoom adjustments, which can be beneficial for video recording or situations where precise zoom control is desired. These lenses often have additional controls on the lens barrel for easy access to the zoom function.
Canon Lens Codes for Specialized Lenses & Features
The codes in this category refer to specialized or niche lenses that are used for specific uses.
- MM – Stands for Macro-Magnification. It refers to lenses that are specifically designed for macro photography, providing a magnification ratio higher than 1:1. Canon’s MM lenses offer an impressive close-up capability, capturing details of small subjects at a higher magnification than standard macro lenses.
- MP-E – Stands for Macro Photo-Electro. This unique Canon lens series is designed for extreme close-up photography, providing magnifications from 1x to 5x life-size. Unlike typical macro lenses, MP-E lenses do not focus to infinity and are intended solely for macro photography. They are popular among photographers who specialize in capturing small subjects, such as insects or tiny details in nature.
- TS-E – Stands for Tilt-Shift Electro. These Canon lenses are designed to offer perspective control and are primarily used in architectural and product photography. Tilt-shift lenses allow photographers to control the plane of focus and the perspective independently, reducing distortion and achieving precise focus across the entire subject.
