Lens manufacturers label their lenses with various abbreviations that describe features and functions of their lenses. Understanding what they describe is important in judging the quality and usage and assist in making a decision on what to purchase.
EF,EF-S, Indicate lenses built for EOS system of cameras.
IS, Image Stabilization, Optical Image Stabilizer. Compensates for lens and camera shake producing a sharper image. See number 1 in additional information.
L, L series of EF lenses. Distinguished by a red ring around the barrel. Generally found on telephoto and zoom lenses and indicating the use of Ultra Low Dispersion glass.
UD, S-UD, Ultra Low Dispersion Glass and Super Low dispersion Glass. See # 2 in additional information.
U, Ultrasonic Motor (USM), for fast focusing with very low noise.
AL, Indicates Aspherical Elements. Used in super wide angle lenses and to correct Chromatic Aberrations. See number 2 and 4 in additional information.
CA, Circular Aperture. Curved aperture diaphragms which create a more rounded aperture.
I/R, Inner and Rear focusing feature. Describes focusing internally, I.e. no extension or retraction of the lens barrel when focusing.
AF-S, Auto Focus Stop. Found on some telephoto lenses. It momentarily locks auto focus to prevent focusing on a passing object in front of the main subject, allowing focusing to occur upon the object passing out of the frame.
EF-S, Lenses designed for 20D, 30d, 40D and Digital Rebel cameras. Digital only lenses. Note these cameras can also use full frame 35mm lenses.
NIKON LENS ABBREVIATIONS
AIS, Aperture Indexing Shutter. All lenses manufactured since 1982, including AF lenses are AIS. Distinguish the lenses with a red or orange marking on the smallest aperture opening, F22 or F32.
AF, Auto Focusing, an auto focusing lens.
AF-I, Auto focusing Indexing. Sends information to the camera body of the aperture in use and the focal length of the attached lens.
AF-S, Auto Focus Silent Wave. Lens that auto focuses with an Ultra Sonic motor.
D, “D”, indicating an end coder which allows for 3D matrix RGB exposure metering for more saturated colors. Distance information is also sent to Nikon speed lights (flash) for adjusting the flash intensity.
ED, Extra Low Dispersion Glass for eliminating chromatic dispersion. See #2 in additional information.
IF, Internal focusing. Focusing takes place within the barrel of the lens.
VR, Vibration Reduction. A form of Optical/Image compensation for lens shake. See #1in additional info.
Helpful Photographic Hints , continued.
DX, Lenses built for digital only cameras .Note the D40 must use DX lenses. All other cameras can use DX lenses and full frame 35mm lenses. The new D3, with a full frame sensor must use full frame 35mm lenses. It is identified with a FX symbol.
NIC, Nikon Integrated Coating. Nikon’s proprietary anti- reflecting coating on all front and back glass surfaces. Reduces reflections, ghosting and flare.
ADDITIONAL INFORMATION
#1, Image Stabilization ( Canon) and Vibration Reduction ( Nikon) are electro-mechanical devices built into the lens that compensates for lens movement during focusing and shutter operation producing sharper images. The lenses may be hand held or on a tripod. Also effectively “adds” 2-3 stops of light allowing for faster shutter speed counteracting for the lens or camera movement.
#2, Chromatic Aberrations (Dispersion of color). Red ,Green and Blue travel at different speed through some optical glass and do not converge at the same plane or point causing colors to be weak. To correct this certain glass and non spherical shapes are used. See #3 and #4 below.
#3, Low Dispersion, Super Low Dispersion ,Ultra Low Dispersion and Extra Low Dispersion glasses are used to adjust the speed of the colors Red, Green and Blue to converge or focus on the same plane or point on film and digital sensors.
#4, Aspherical Elements- lens elements with varying curved surfaces (Aspherical ) that correct for Chromatic Aberrations. Sometimes called an Aspherical lens.
Note .The above information has been summarized and is based on literature from Canon and Nikon.
