I am sure that at some point you have looked at your lens and said to yourself “I wonder what all the numbers and letters mean?”, so I decided to write a little about each letter or number for the most common lens makes.
So for example: AF-S Nikkor 18-105mm 3.5-5.6 G ED
AF-S: Autofocus Silent: Focusing is driven by a “Silent Wave” motor in the lens instead of the focus drive motor in the camera. AF-S lenses focus faster than standard AF-Nikkors and almost completely silently. AF-S lenses with a “II” designation weigh less and are generally smaller than their equivalent predecessors.
18-105 mm is the focal length, you will find a variety of different zooms, for example 18-55,mm or 55.200mm etc., there are lenses that are zoom and some are prime lenses, prime lenses will only have one number before the mm, for example 50 mm. This is for all lens makes.
3.5-5.6: this will also depend on the lens, but it refers to aperture, so at 18mm the widest aperture is 3.5 and at 105 mm the widest aperture is 5.6, there are lenses that have a widest aperture of 2.8 throughout the zoom, these are expensive lenses. This is for all lens makes.
G: The lens has no aperture control ring and is designed to be used with cameras that allow setting the aperture from the camera body. G lenses also provide Distance information to the camera.
ED: Extra-Low Dispersion glass: High-quality glass that corrects for chromatic aberration, a type of image and color distortion that occurs when light rays of varying wavelengths pass through optical glass and don’t converge or focus at the same point. Nikkor lenses with ED glass deliver superior sharpness and contrast, even at maximum aperture. Super ED glass is a new type that is used together with ED glass in some lenses to achieve an even higher degree of freedom from chromatic aberration.
VR – “Vibration reduction”
DX: The lens is specifically designed for use on Nikon digital SLR cameras. It produces a smaller image circle for more efficient coverage of the imaging sensor in these cameras, which is smaller than the 35mm film frame.
M/A: A focusing mode on some AF-Nikkor lenses which allows switching from automatic to manual focusing with virtually no lag time by simply turning the focusing ring on the lens.
A Canon EF-S lens is designed for EOS digital SLRs with an APS-C sized sensor. EF-S lenses are a subset of the Canon EF mount. The S in EF-S stands for ‘short back focus’, referring to the distance between the rear element of the lens and the sensor is shorter. EF-S allows lighter, smaller lens designs that cost less to be produced. EF-S lenses are not suitable for full-frame EOS digital SLRs and mounting the lens may cause serious damage to the camera.
Canon L-series lenses are top-end, professional Canon lenses. L-series lenses are sometimes dubbed ‘Luxury’ lenses. The ‘L’ moniker is reserved for professional Canon lenses, which tend to have extra weather sealing, a constant maximum aperture and superior optical performance. You can spot many L-series lenses thanks to the distinctive red ring around the lens barrel. L-series lenses include a lens hood (to reduce the chance of unwanted flare and protect the front element) and a lens pouch.
The USM label means the lens features an Ultrasonic Motor Drive. Canon USM lenses allow quick, accurate autofocus, which also produces less noise than traditional autofocus systems. There are two types of USM found in Canon lenses: Ring-type USM (premium) and micro-motor USM (value). Ring-type USM has the advantage of full-time manual focus, which allows you to adjust the focus manually without switching between AF and MF modes.
DO stands for diffractive optics, a special glass designed to reduce chromatic aberration and allow a shorter lens design. You can spot a Canon DO lens thanks to the thin green ring around the lens barrel.
Sigma DC lenses are designed for digital SLRs with ‘cropped’ sensors. Cropped sensors are smaller than traditional 35mm film or full-frame sensors. Sigma DC lenses are suitable for cameras with APS-C size or cropped sensors that need a smaller image circle to cover the sensor, compared to conventional lenses.
OS designates the lens has Optical Stabilisation built-in. Sigma OS lenses compensate for camera shake which can blur images at slow shutter speeds or whilst hand-holding telephoto lenses.
HSM stands for Hyper-Sonic Motor, a type of autofocus motor that provides fast, accurate autofocus whilst making less noise than traditional autofocus.
Sigma EX denotes greater optical quality and superior build quality. Sigma EX lenses used to have a distinctive crinkle finish, but this has recently been replaced with a matte black finish.
Tamron VC lenses are designed reduce image blur from camera shake. The Tamron Vibration Control (VC) technology corrects for camera shake at 4000 times per second, for a smooth stabilized view in both the viewfinder and your image. The VC system also allows you to pan without changing any settings.
Tamron PZD stands for Piezo Drive, a form of ultrasonic autofocus. Tamron PZD lenses offer you fast but silent autofocus, in a more compact lens size than traditional ultrasonic autofocus motors.
Tamron USD stands for ultrasonic drive, used for fast and smooth autofocus. Tamron USD lenses use deflective traveling waves to drive a rotor, moving elements within the lens to focus your image.
Tamron XR denotes the lens has extra-refractive glass, allowing Tamron to make the lens barrel shorter whilst retaining the same optical quality.
Tamron Di II lenses are designed for digital SLRs with ‘cropped’ sensors. Tamron Di II lenses are specifically designed for cameras with APS-C size sensors, whereas the Tamron Di series (without ‘II’) are compatible with full frame and APC-S digital SLRs.