AF — The original autofocus designation, indicating focus driven by a motor inside the camera body. All AF lenses have a CPU.
AF-D — Official Nikon designation for an AF lens (as above) with “D” functionality (see “D” below).
AF-I — Autofocus-Internal. Driven by a coreless DC motor. Used only in long telephoto lenses (300 mm f/2.8 through 600 mm f/4.0) starting in 1992. Replaced with AF-S in 1996.
AF-S — Autofocus-Silent. Uses a “Silent Wave Motor” (ultrasonic motor) to focus quietly and quickly. Similar to Canon’s “USM” technology. Introduced in 1996.
AF-N — Indicates the “New” version of an AF lens. The change from plastic focus rings on early AF lenses to the a new “rubber inset focus ring” (RIFR) is often indicated by the AF-N designation.
E — Electromagnetic diaphragm. The aperture diaphragm of an E lens is controlled digitally by the camera, and actuated electromagnetically by a system housed within the lens, rather than employing the F-mount’s traditional mechanical diaphragm linkage. Currently this system appears only in certain Perspective Control lenses, designated PC-E, with designs that preclude a mechanical linkage. The E feature is only supported by the Nikon D3, D3x, D700, D300, and D300s cameras. PC-E lenses require manual diaphragm operation on other cameras. Not to be confused with Series E lenses.
G — Indicated after the f-number. G lenses do not have an aperture ring, and the aperture can only be controlled electronically by the camera body. Only autofocus bodies with command dials are capable of controlling G lenses. Older autofocus bodies will work with G lenses in shutter priority and program modes with full opened aperture. Some recent G lenses feature a gasket around the mounting flange. G lenses otherwise have the same characteristics as D lenses.
VR — Vibration Reduction. Uses a moving optical group to reduce the photographic effects of camera shake. Some VR lenses also support a panning mode, detecting horizontal movement of the lens and minimizing only vertical vibration. The second generation of VR is called VR II, which is designed to offer another 1-stop advantage over original VR, but lenses with this feature are still designated simply “VR.”
AI-P or P — “AI with Program.” CPU-enabled variation of AI-S. Includes only the 45/2.8P, 500/4P and 1200-1700/5.6-8P. Not to be confused with early lenses marked “Nikkor-P” meaning a 5-element lens (see pre-autofocus designations above).
CPU — Central Processing Unit. The lens is fitted with electrical contacts for digital communication with the camera. All AF and AI-P lenses are CPU lenses. Some non-professional Nikon cameras require CPU lenses for metered operation. This designation appears in specifications but not lens names.
D — Distance. Indicated after the f-number (often designated AF-D). It means the lens is capable of using Nikon’s 3D Matrix Metering on bodies that support it. The lens transmits focus distance information, which is incorporated into the camera’s exposure calculations in 3D Matrix Metering mode. Not to be confused with early lenses marked “Nikkor-D” meaning a 10-element lens (see pre-autofocus designations above). All AF-D, AF-I, AF-S, G, and VR lenses have full D-functionality. AF-D lenses do not have focusing motors; they must be autofocused by a motor in the camera.
CRC — Close Range Correction. Improved performance at close focus distances. Achieved by internal focus movements that are complex with respect to movement of the focus ring. This designation appears in specifications but not lens names.
DC — Defocus Control. DC lenses have a separate control ring for spherical aberration, which affects primarily the appearance of out-of-focus areas, also known as bokeh. At extreme settings, DC lenses can generate an overall soft-focus effect. Includes only the AF DC-Nikkor 105mm f/2D and AF DC-Nikkor 135mm f/2D.
ED — “Extra-low Dispersion” glass incorporated to reduce chromatic aberration. “Super ED” glass has been introduced as well.
GN — Guide Number. Assists in flash exposure on cameras without automatic flash metering. The flash’s guide number is set on the lens, and the aperture is accordingly coupled to the lens’s focus ring for correct exposure.
IF — Internal Focus. Focusing is accomplished through the movement of internal lens groups, eliminating extension and rotation of the front lens element, and allowing focus to be driven quickly by a small motor.
Micro — Micro lenses are capable of high reproduction ratios, typically 1:2 or 1:1, for macro photography.
N — Indicates the Nano Crystal Coat, a relatively new type of lens coating that originated in Nikon’s semiconductor division. Lenses with this coating feature the logo of an “N” inside an elongated hexagon on the name plate.
PC — Perspective Control. Lens features shift movements (and also tilt movements on some models) to control perspective and depth-of-field. Newer PC lenses are designated PC-E (see electromechanical designation E above). Not to be confused with early lenses marked “Nikkor-P·C” meaning a 5-element coated lens (see pre-autofocus designations above).
Reflex — Designates a catadioptric (mirror) lens.
UV — Lenses designed for imaging ultraviolet light.
DX — Lens designed for the smaller Nikon DX format. Vignetting may occur if used on a 135 film or Nikon FX format camera in full-frame mode, although some DX lenses cover the full 135 frame at longer focal lengths.
Nikon AF-S/Sigma HSM: The lens contains an integrated ultrasonic focus motor, which enables fast and quiet autofocus operation. All Nikon zoom AF-lenses have focal length encoders added.
Nikon AF-I: The lens contains an integrated focus motor. This type was produced from 1992 to 1996 and is rarely seen.
Nikon DX/Sigma DC/Tamron Di-II/Tokina DX: Denotes a lens that is designed for APS-C (or “cropped”) DSLR sensors. Use of this lens on an full-frame (FX) sensor will likely cause vignetting. Contemporary full-frame Nikon DSLRs are able to detect DX lenses and crop the image accordingly.
Sigma DG/Tamron Di: A lens for fullframe-sensors (FX) or analog film. No special designation for Nikon NIKKOR.
Nikon VR/Sigma OS/Tamron VC: Vibration Reduction, a system used to compensate for vibration and other camera movement.
Nikon D: The lens is fitted with a digital sensor that tells the camera the distance at which it is focused, to allow for better exposure calculation.
Nikon G: The lens is not fitted with an aperture ring, and is thus incompatible with some very old Nikon film SLR bodies. All G-type lenses are also D-type.
Nikon ED/Sigma APO/Tamron LD: Indicates that the lens is fitted with Extra-Low Dispersion glass, which aids in reducing chromatic aberration and flare.
Sources from Wikipedia