Note: with pre-AI lenses Nikon often used a single letter abbreviation to indicate the number of elements in the lens: U (uni) =1, B (bi) =2, T (tri) = 3, Q (quadra) = 4, P (penta)-5, H (hexa) = 6, S (septa) =7, O (octa) = 8, N (nona) = 9, and D (deca) = 10). Usually these letters were appended to Nikkor, as in Nikkor-Q 135/2.8, which would be a pre-AI 135mm f/2.8 lens with four elements (Q). Keep that in mind when deciphering the alphabet soup Nikon has used over the years. If you’re dealing with a really old lens, a single letter alongside the Nikkor is likely to refer to elements, not the terms shown below.
A — The original bayonet lens type (1959). Manual focus lens. Considered Pre-AI
ADR — Aperture Direct Readout. A fancy way of saying that aperture scale can be seen directly by the cameras that have overhanging prisms (ala F4, F5). Started with AI lenses in 1977.
AF-I — An autofocus lens with an Integrated, coreless focus motor (1992). All AF-I lenses are D-type, but some older film bodies can’t autofocus with them (N60, N8008).
AF-S — An autofocus lens with a Silent wave, integrated, coreless focus motor (1996). Basically an update to AF-I. Some older bodies can’t autofocus with them (N60, N8008). Some newer bodies (D40, D40x) can only autofocus with them.
AI — Aperture Indexing (1977). Manual focus lens.
AI-P — An AI lens variant (1988) that was “chipped” to send data to the camera.
AI-S — A variant of AI designed to be used with Program and Shutter-priority exposure modes (1982). Manual focus lens. Distinguished by smallest aperture being printed in orange and a small scoop on the bayonet flange, which transmits aperture info. Otherwise same as AI.
ASP — Lens has aspherical elements in its optic design. Aspherical lenses eliminate coma and other types of lens aberrations by using complex curves in the design of lens elements.
C — A lens coating type (Nikon Integrated Coating) for Pre-AI lenses. Distinguished by a C after the lens designation and a black filter ring.
CRC — Close Range Correction, means that the lens was designed to provide superior focusing at close distances and with flat fields.
D — (1992) Adds distance information to the data transmitted to the camera via chip. Distinguished by the D or G after the lens designation.
DC — Defocus Control lens, allows the photographer to change the degree of spherical aberration in the out-of-focus areas to provide for better bokeh.
DX — (2003) Indicates a lens designed to cover the smaller image circle of the digital camera bodies. May still work on 35mm bodies at some focal lengths.
E — A special type of AI lens (1977) introduced with the consumer-oriented EM body. Says Nikon Series E on the lens. Light in weight, plastic in construction, but optically good.
ED — Extra-low Dispersion element(s) used in the lens.
FX — (2007) 35mm full frame digital sensor. While Nikon doesn’t explicitly use this acronym yet with lenses, it has used it casually to refer to lenses that cover the full 35mm film (and FX digital sensor) frame, as opposed to lenses that cover smaller imaging sizes, such as DX or IX.
G — Removes the aperture ring from a D-type lens. Thus needs to be used on camera with Command dial control of apertures. With some older cameras (N90s, for example), can be used in Program or Shutter-priority exposure mode, though.
IF — Lens uses internal focusing rather than moving or turning outer elements.
IX — Lenses for the Pronea system (Advanced Photo System). Can’t be used on the 35mm or digital bodies.
K — Another Pre-AI lens type, this time with rubber focus rings.
N — Originally, the actual designation used for the first AI lenses; beginning in 2005 it now stands for Nano Crystal Coat, a special type of flare reduction coating applied to newer lenses.
N (gold emblem)– Nano coating. A crystalline coating that eliminates internal lens element reflections, reducing ghosting and flare.
NIC — Nikon Integrated Coating. A fancy way of referring to Nikon’s glass coating system, which is used to help reduce flare and ghosting.
PC — Perspective Control lens, allows the front of the lens to be shifted relative to the rest of the lens to correct for perspective. All PC lenses are either AI or AI-P in type.
RF — Rear Focusing, means that lens achieves focusing by moving the rear elements; similar to IF.
SIC — Super Integrated Coating, a multi-layer flare reduction coating, usually applied to the more complex zoom lenses.
SWM — Silent Wave Motor. This is the motor in the lens used in AF-I and AF-S lenses.
UW — Underwater lenses, destined for the Nikonos systems.
VR — Vibration Reduction lens, corrects for camera movement during exposure. VR function only works on post F5 cameras (e.g., not F4, N90s, N60, N70, N8008). Lately, Nikon has been using a VRII designation to indicate some advances to the vibration reduction system.