Every Canon and Nikon lens has a model name infused with a string of semi-confusing acronyms that describe the features and technology found in the lens itself. Knowing what these acronyms stand for will make deciphering a lens’s name much easier, helping you to choose the lens with the specific features are you looking for. Let’s get started!
Canon Lens Terminology
Electro-Focus: The Canon EF lens mount is used for the company’s pro lenses and is a lens with an electric mount (as opposed to a mechanical mount). These lenses have a built-in motor for auto-focus. The EF mount has been around since 1987.
The EF-S mount is relatively new, and was introduced in 2003 for “crop sensor” bodies such as the Digital Rebel and 40D/50D series of camera bodies. The EF-S camera bodies will work just fine with EF lenses (though images are cropped), but EF lenses do not mount to EF-S bodies. This means you can put an L lens on a Rebel, but you can’t put an EF-S lens on a 5D Mark II.
Ultra-Sonic Motor – This is Canon’s best auto-focus system and is regarded as silent, fast and accurate. Lenses that bear the letters USM at the end of their name employ this technology.
Lenses with the designation of “L” are Canon’s top-of-the-line EF lenses. Canon claims the L stands for “Luxury,” but some have suggested it’s more likely that it stands for “low dispersion,” which are the elements inside the lens – known as UD elements for “ultra low dispersion” – that help contribute to the lenses’ superior optical performance. Considered Canon’s “professional” series, all L lenses have a red ring around the end of the lens barrel signifying their awesomeness. Canon’s super-telephoto L lenses feature the familiar white paint job, helping to separate themselves from any black lenses that might be nearby.
Image Stabilization: Canon’s IS technology help control camera shake that results from shooting handheld. The lens is able to detect movement and optically correct the resulting shake, allowing the shooter to use a lower shutter speed than if they were using a lens without IS. You can watch Canon’s promo video for IS here.
Mark I, Mark II
From time to time Canon will create an improved version of an existing lens, at which time the previous lens becomes a Mark I (although there is no official designation for this) and the new lens becomes a Mark II, signified by a II in the lens title. Typical changes to a Mark II lens include improved optics, lighter weight and improved image stabilization performance, as we’ve seen with the new 70-200mm f/2.8 L IS II USM.
These are Canon’s tilt-shift lenses, which allow you to tilt and shift the focus plane of the lens to correct distortion in a scene that typically results in converging lines within a scene, which appears unnatural. With a tilt-shift lens you can keep straight lines straight, so it’s useful in architecture and when shooting the interiors or exteriors of buildings. A tilt-shift lens can also be used to apply selective focus, which is used to create the popular “miniature scenes” you have seen on the Internet.
Diffractive Optics: There are only two DO lenses available; the 400mm f/4 IS DO and the 70-300 f/4.5-5.6 DO. They mark an effort by Canon to drastically reduce the size and weight of a lens, and Canon was successful too we might add; these lenses are incredibly light and small given their focal lengths. That said, Canon has not announced a new DO lens in years, so it’s likely this will be a designation that will go the way of the Dodo bird eventually.
Nikon Lens terminology
You won’t see a Nikon lens be listed as “F mount” because they all are, but since Canon specifies what mount the lens has we thought we’d put it in here. Nikon’s F mount was adopted in 1959 and has over 400 compatible lenses including everything you will find on our website.
Auto-Focus Silent: This is Nikon’s high-end auto-focus system and the “S” stands for Silent Wave Motor, meaning the motor driving the AF in the lens is “silent.” This is Nikon’s fast, quiet auto-focus, and it appears on almost all of their new lenses.
If you just see the letters AF on the lens barrel, that means it does not use the Silent Wave Motor, but a traditional motor instead. This means you can actually hear the AF working (though it’s not that noisy) and it can be a tad slower than what you get on an AF-S lens, depending on the lens. This auto-focus system is almost exclusively found on older Nikon lenses.
The “D” designation stands for “distance,” so when you take a meter reading with a D lens it can tell the camera body the distance which it is focused. This feature is found on older lenses, as newer lenses feature the AF-S designation.
This stands for Extra Low Dispersion glass elements that are within the lens that help control dispersion when light enters the lens. Though not quite as exclusive as Canon’s L designation, the ED badge is stamped onto all of Nikon’s professional lenses, but some of their consumer lenses as well so it’s not a guarantee of “best in class” performance.
This designation stands for a lens has no physical aperture ring. This helps reduce the size and weight of the lens but means the lens won’t work properly on some older camera bodies. All of Nikon’s new lenses are G-type lenses.
Vibration Reduction: This is Nikon’s version of image stabilization, known as Vibration Reduction. It detects and helps eliminate camera shake that occurs when shooting handheld. It’s very useful on longer focal length lenses but typically doesn’t appear until you get into the 200mm focal length. There is a new 16-35mm ED VR lens, however.
Nano Crystal Coating
This is the good stuff – only Nikon’s best stuff gets this treatment, which consists of sub-atomic particles applied to one element inside the lens to prevent flare and ghosting caused by reflections occurring inside the lens barrel. This would occur when light enters the lens at an angle. The nano crystal coat helps bend the light into the lens, preventing the light from bouncing around and causing flare.
DX and FX
Some Nikon lenses have a DX badge on the barrel, but FX lenses are lacking any such designation. The absence of the DX badge lets you know they are FX lenses, and are therefore compatible with full-frame cameras such as the D3, D700 and others. DX lenses are designed for crop-sensor camera bodies such as the D40/50 and D300. These DX bodies can use FX lenses without issue. Full-frame bodies can also use DX lenses, but only a small portion of the center of the frame is usable and the pixel count is diminished significantly.
This stands for Internal Focusing, meaning the actual lens itself doesn’t move in and out to focus, but just the internal elements move. This helps keep lens size down, and also allows for faster focusing since the physical barrel of the lens isn’t moving back and forth.
Defocus Control: There are only two of these lenses from Nikon and they are older, but they allow you to adjust the aperture of the background by spinning a dial on the lens itself. For example, you can shoot at f/2 and then have the background be f/5.6.
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