When we think about buying a new camera, our first concern is usually the camera body itself. We think about the features and functions that are important to us and try to find a model that fits our criteria. But many people don’t give enough thought to the lens that goes with the body, when in reality the lens has a huge effect on the quality and style of the final image.

Today we’re going to take a look at some of the features commonly found on lenses, and also the numbers, letters and acronyms attached to those lenses that can be kind of intimidating, but are important to understand so that you can assess the capabilities and limitations of various lenses. In many cases the designation is a way of separating premium lenses from standard ones, and these are the ones you’ll most often hear the gearheads bandying around.

Now there are literally hundreds of acronyms and designations out there, so I’ve decided to narrow things down to just those that you’ll find on lenses available through BestBuy.ca.

The first thing I want to look at is the focal length. This is pretty straightforward, and widely understood, but worth mentioning for completeness. If you buy a prime lens, you will see just one number, which refers to the fixed focal length of that lens. The two most popular primes are probably the 35mm and the 50mm. I personally love to shoot with my Canon 50mm. It’s small, light, and makes fantastic images. Most camera kits are sold with a zoom lens however, which allows you to zoom in on your subject without changing position. For example the Canon Rebel T3i comes with an 18-55mm lens, as pictured.

The next little piece of information that you’ll want to take note of is the maximum aperture of the lens. (If you’re unfamiliar with what the aperture number is, take a look at this piece I wrote a few weeks back). The aperture number is often written like this: f/2.8, f/5.6, f/11. But on the actual lens it is written like this: 1:2.8, 1:5.6, 1:11. On some lenses, and in particular the more budget or entry-level units, the maximum aperture will actually vary across the focal length range. So for example on the Nikon D3200 (pictured), you’ll see the numbers ‘1:3.5-5.6’. This indicates that there is a range of maximum apertures, depending on the focal length. So at the minimum focal length (18mm in this case) the maximum aperture is f/3.5, and at the maximum focal length (70mm in this case) the maximum aperture is f/5.6.

So that covers the terminology that is common to all lens types. Now I’m going to look at the various acronyms used by the various manufactures, and explain what those acronyms mean.

EF (‘Electro-focus’): Refers to the lens mount used by Canon EOS film SLRs and full-frame DSLRs.
EF-S: Refers to the lens mount used by Canon EOS DSLRs which have the smaller APS-C sensor.
L: Refers to Canon’s premium range of lenses, like the 24-105mm f/4 L. They have a signature thin red hoop which makes them easy to spot.
USM (‘Ultrasonic Motor’): A drive motor for the autofocus system. Provides faster, more accurate, and quieter focus than a conventional electromagnetic drive motor.
IS (‘Image Stabilisation’): The system which compensates for camera shake and allows you to shoot at lower shutter speeds. Included on the 70-200mm f/4L.

Although it was once the designation for Nikon’s premium lenses, all Nikon lenses are now branded as ‘Nikkor’ lenses.
FX: Designates lenses designed to be used with Nikon’s film cameras and full-frame DSLRs
DX: Designates lenses designed to be used with Nikon’s cameras with the smaller APS-C sensor.
AF (‘Auto-focus’): Simply refers to the fact that the lens has an autofocus motor.
AF-S (‘Auto-focus Silent’): Like Canon, some Nikkor lenses have an ultrasonic motor (known as ‘Silent Wave Motor’ or ‘SWM’) for improved autofocus performance.
VR (‘Vibration Reduction’): Similar to Canon’s ‘IS’. There is also a ‘Vibration Reduction II’ system which is a better, more advanced system, as used by the 70-200mm f/2.8 (pictured).
IF (‘Internal Focus’): Refers to the fact that all optical element movements take place inside the camera, where often an element will move out of the front of the lens as you zoom in.
ED (‘Extra-Low Dispersion’): Refers to a type of glass which has been used in the manufacture of the lens which reduces chromatic aberration, a kind of color distortion, which you often see when you look very closely at an image. The 10-24mm f/3.5-4.5 is an ED lens.
G: Refers to lenses which do not have an aperture control ring, which are pretty uncommon nowadays anyway. Nikon should probably drop this designation to simplify things.

E-mount: Designates lenses for the NEX range.
OSS (‘Optical SteadyShot’): Refers to Sony’s image stabilzation system.
T*: Refers to a special anti-reflective coating on Carl Zeiss manufactured lenses.
FE: Refers to E-Mount lenses for full frame mirrorless cameras, like the A7 and A7R.
ZA (‘Zeiss Alpha’): Refers to premium lenses manufactured by the Carl Zeiss company for Sony Alpha cameras, like the 55mm f/1.8.
SAM (‘Smooth Autofocus Motor’): Refers to the drive motor in budget Sony lenses.
DT (‘Digital Technology’): Refers to lenses which work with Sony’s DSLRs with APS-C size sensors.

XF: Refers to Fujifilm’s premium line of lenses.
OIS (‘Optical Image Stabilization’): Refers to Fujifilm’s image stabilization system

AF (‘Auto-focus’): Simply refers to the fact that the lens has an autofocus motor.
Di (‘Digitally integrate’): Lenses usable on 35mm film SLRs or full-frame DSLRs.
Di II: Lenses usable on cameras with APS-C sensors only
VC (‘Vibation Compensation’): Refers to Tamron’s image stabilization system
USD (‘Ultrasonic Silent Drive’): Tamron’s standard ultrasonic drive motor implementation
PZD (‘Piezo Drive’): Tamron’s premium ultrasonic drive motor implementation
XR: Refers to the Extra Refractive Index glass used in some lenses, which allows for decreased lens size without sacrificing image quality.
SP (‘Superior Performance’): Indicates a lens from Tamron’s premium line.

DG: These lenses are usable with 35mm film cameras, but are specifically designed for full-frame DLSRs
DC: Refers to lenses desinged to work with cameras with APS-C size sensors
EX: Refers to Sigma’s premium lens range.
HSM (‘Hyper Sonic Motor’): Sigma’s ultrasonic drive motor implementation for autofocus.

As I mentioned before, there are lots more lens designations, but hopefully we’ve removed a little bit of the fear factor surrounding them today. If there’s one you see on your lens that I haven’t covered, do a little online research and I’m sure you’ll find the answer in no time.