Lenses with Arc-Form Drive, the first autofocus motor used in Canon EF lenses. It is much louder than USM motors, somewhat slower and not as quick. It also has slower reaction time so does not follow subjects as well as newer motors. There is no full-time manual focus override. If an autofocus Canon lens has no indication on its barrel what sort of AF motor is used, it is either AFD or Micro Motor.
DO
Lenses with Diffractive Optics which bends light more than regular glass which allows them to be smaller than regular lenses of the same parameters.
EF
Stands for both a Canon lens mount and Canon lenses that are designed for cameras with fullframe sensors.
EF-S
Canon lenses that are designed for cameras with APS-C sensors. These can be mounted on cameras with fullframe sensors and EF mount but the camera will only work crop-mode.
EF-M
Stands for both a Canon lens mount and Canon lenses that are designed for mirroless cameras with APS-C sensors. These can't be mounted on DSLR cameras with an EF mount because of the reduced flange focal distance of the EF-M mount.
FD
Stands for both a legacy Canon lens mount and legacy Canon lenses. These were not suited for autofocus, Canon discountinued them in 1987.
FDn
Same as FD, only with no coating designation. By default they used SSC lens coating.
FL
Same as FD but without the ability to meter at full aperture.
I, II, III
Describe lens' generation. If a lens gains image stabilization it drops the previous numercal and should be considered a newer release.
IS
Canon's Image Stabilization.
L
Canon's "Luxury" lenses, their high-end product line. Most of these also have weather protection. They can be recognized by the signature red ring at the end of the lens.
Macro
Macro lenses are designed for extreme close-ups and usually required to have at least 0.5 maximum magnification.
Micro USM
Lenses with a smaller version of Canon's UltraSonic Motor for autofocus. These generally don't allow for manual override of autofocus.
MM
Lenses with Micro Motor for autofocus, Canon's least advanced autofocus motor and the smaller version of the AFD motor. Does not allow for manual focus override.
MP-E
Macro lens with maximum magnification of more than 1x.
PZ
Lenses with Power Zoom, a dedicated motor to change the focal length of the lens.
Softfocus
Lenses which have optical formula that is meant to deliver softer results on purpose.
SSC
Legacy lenses with "Super Spectral Coating" which minimizing lens reflections and increases contrast.
STM
Lenses with Stepper Motor for autofocus which is designed to minimize autofocus vibration and noise during video recording. They are also focus-by-wire, meaning turning the focus ring does not physically move the elements.
TS-E
Tilt-shift lenses, i.e. tilt and shift adjustments that allow for changing the angle of the focal plane.
USM
Lenses with UltraSonic Motor for autofocus.
Fujifilm
ALG
Lenses with All-Group Focusing meaning all the lens' element are moved during focusing which maximizes optical performance throughout the focus range.
DM
Legacy lenses with Dial Mode, an automatic aperture control that can be used in Program, Shutter-priority, Aperture-priority, and Manual exposure modes by cameras that support them. Non-DM lenses can only be used in Aperture-priority and Manual modes.
EBC
Lenses with Fujifilm's Electron Beam Coating which is used to minimize flare and ghosting produced by the lens by increasing the light transmittance so that more light passes through the glass towards the sensor, and less of it gets reflected. It also increases contrast and is basically similar to multi-layer coatings developed by other lens manufacturers in its function.
F
Legacy fisheye lenses.
HT-EBC
Broadcast lenses with an improved version Fujifilm's Electron Beam Coating which is used to minimize flare and ghosting produced by the lens by increasing the light transmittance so that more light passes through the glass towards the sensor, and less of it gets reflected. It also increases contrast and is basically similar to multi-layer coatings developed by other lens manufacturers in its function.
LM
Lens using linear motor for their autofocus.
OIS
Lenses with Fujifilm's Optical Image Stabilization.
M
Legacy macro lenses.
Macro
Macro lenses are designed for extreme close-ups and are usually required to have at least 0.5x maximum magnification.
R
Lenses with a dedicated aperture ring. The aperture ring controls the aperture electronicaly rather than mechanically.
SW
Legacy super-wide angle lenses.
T
Legacy telephoto lenses.
W
Legacy wide angle lenses.
XC
Fujifilm's budget product line, which are generally cheaper and simpler than their XF lenses. Their optical performance is still better than budget lenses of other brands, they are just designed to be compact, lightweight, and affordable.
XF
Fujifilm's high-end product line. They usually have metal barrels and wider-than-average apertures, and Fujifilm's best technology in general.
Z
Legacy zoom lenses.
Nikkor
AF
Autofocus lens, meaning the camera controls where the lens is focusing automatically without you needing to adjust the focus manually using the focus ring.
AF-I
Autofocus lens (see AF), with an integrated autofocus motor (as opposed to motor being inside the camera).
AF-S
Autofocus lens (see AF), specifically using Nikkor's "Silent Wave Motor"
AF-P
Autofocus lens (see AF), specifically using Nikkor's "Stepping Motor"
AI
"Automatic Indexing". Was used on very old manual focus lenses and it's no longer used on modern lenses.
AI-P
Manual lenses with "Automatic Indexing" and a chip that sends data to the camera. No longer used on modern lenses.
CRC
"Close Range Correction". Lenses that are optimized for close focusing distances.
D
Lenses that send distance information (distance from subject) to the camera.
DC
"Defocus Control". Lenses that allow controlling the bokeh.
ED
Lens that contains "Extra-low Dispertion" elements.
DX
Lenses for cameras with APS-C sensor. While these can be mounted on fullframe cameras if the lens mount matches, the camera will only work in APS-C mode or will produce heavy vignetting.
FX
Lens for camera with fullframe sensor. Not used in descriptions because it's assumed the lens is for fullframe sensor unless stated otherwise.
G
Lens that does not have an aperture ring.
IF
Lens with "Internal Focusing", meaning the lens can focus without extending the barrel. Can focus faster than lenses without internal focus. Useful for using with gimbals because the weight distribution doesn't change.
HRI
Lens that contains "High Refractive Index" elements
Micro
Same as "Macro", used for close-up work. Macro lenses usually require maximum magnification of at least 0.5x.
N
Lens with "Nano Crystal Coating". Used on the lens itself, not in the name.
PC-E
"Perspective Control" with electronic diaphragm. Allows lenses to tilt and shift to create special effects.
RF
Lens with "Rear Focusing", meaning it focuses by moving the rear element inside the lens.
SIC
Lens with "Super Integrated Coating". Used to achieve better color performance and to better deal with ghosting and flaring.
SWM
Lens with "Silent Wave Motor" which allows for adjusting the focus using the manual focus ring while in the autofocus mode.
Art product line. Sigma's highest quality, fastest prime lenses.
APO
Apochromatic lenses. These are designed to correct chromatic and other abberations.
ASP
Lenses with Aspherical glass elements.
C
Contemporary product line. Consists mainly of Sigma's budget, variable aperture zoom lenses for general use.
Conv
Can be used with Sigma teleconverters.
DC
Lenses for cameras with APS-C sensors.
DF
"Dual Focus", lens that does not rotate when focusing.
DG
Lenses for cameras with fullframe sensors.
DN
Lenses for compact system cameras
ELD
Lenses with Extraordinary Low Dispertion glass elements that are designed to minimize chromatic abberation. Should be better that lenses with SLD elements.
EX
Sigma's old high-end lenses. No longer used on new lenses.
FLD
Lenses with "FLow Dispertion" glass elements, Sigma's "highest level low dispection glass available with extremely high light transmition". It should perform as well as flourite elements but is far less expensive.
Fisheye
Fisheye lenses have very wide angles of view (up to full 180°) with the signature strong distortion.
HSM
Lenses using Sigma's "Hyper Sonic Motor" for their autofocus.
IF
Lenses with internal focus. These lenses don't extend when focusing.
MACRO
Macro lenses are designed for shooting extreme close-up image. Macro lenses can be recognized by having at least 0.5x magnification. In Sigma's case macro lenses do not always satisfy this requirement.
OS
Lenses with optical stabilization
RF
Lenses with rear focus, meaning the lens focuses by moving its rear glass elements.
S
Sport product line. Sigma's telephoto lenses designed for shooting sports and wildlife photography.
SLD
Lenses with "Special Low Dispertion glass element that are designed to minimize chromatic abberation.
TSC
Lenses using Thermally Stable Composite, special material that blends qualities of polycarbonate and metal. According to Sigma, it “offers 25% greater elasticity than polycarbonate. Since its thermal shrinkage is low, TSC matches well with metal parts, further contributing to the high-precision construction of the lens.”
Sony
DT
"Digital Technology" lenses, which are designed for cameras with an APS-C sensor. These can be mounted on cameras with fullframe sensors but the camera will be in crop mode.
E
Lenses designed for mirrorless cameras with APS-C sensors.
ED
Lenses with Extra-low Dispersion glass elements which are designed to reduce chromatic abberations.
FE
Lenses designed for cameras with fullframe sensors.
G
Sony's "Gold" lenses, which is their highest-quality product line.
OSS
Lenses with Sony's "Optical SteadyShot", their optical image stabilization.
PZ
Lenses with Power Zoom which means they have inbuilt motors to operate the optical zoom. Useful for videography for the lens' ability to zoom smoothly.
SAM
Lenses using Smooth Autofocus Motor for their autofocus. Used in Sony's lower-end lenses.
SSM
Lenses using SuperSonic Motor for their autofocus.
STF
Lenses with Smooth Transition Focus that employ special APD lens groups
ZA
Zeiss Alpha lenses, Zeiss branded lenses designed specifically for Sony cameras and, as far as high-quality goes, these are on par with Sony’s G lenses. Designing and manufacturing these lenses is still up to Sony, but only when the optical design is approved by Zeiss according to their high standards.
Tamron
AD
"Anomalous Dispertion", lens designed to reduce chromatic abberation.
ASL
Lens with Aspherical glass elements
Di
Tamron lenses designed for cameras with a fullframe sensor.
Di II
Tamron lenses designed for cameras with an APS-C sensor.
Di III
Tamron lenses designed specifically for mirrorless cameras.
FTM
Lenses with full-time autofocus, meaning the focus can be manually adjusting by turning the focus ring even when the lens is in autofocus mode.
IF
Lenses with Internal Focus.
LD
Lenses with Low Dispertion elements which compensate for chromatic abberation.
OSD
Lenses with "Optimized Silent Drive" for autofocus.
PZD
Lenses with "Piezo Drive" for autofocus.
RD
Lens with rounded diaphragm (aperture) blades to produce a more circular bokeh.
RXD
Lenses with "Rapid Extra Silent Stepping Drive" for autofocus
SP
Tamron's Super Performance series, their high-end product line.
USD
Lenses with Ultrasonic Silent Drive for autofocus.
VC
Lenses with Vibration Compensation, Tamron's optical image stabilization technology.
XR
Lens with Extra Refractive glass elements for improved optical results.
ZL
Lens with zoom-lock, the ability to lock the zoom so that the barrel doesn't extend from the effect of gravity.