Here are the main Nikon Terms
Nikkor is the branding applied to lenses made by Nikon.
- AI, AI-S: Nikkor lenses produced after 1977 have an automatic indexing feature that eliminated the need to manually align the aperture ring when the lens was mounted. The first lenses to include this feature had the AI or AI-S designation. However, all optics introduced after 1977 have automatic indexing (except for G Series lenses, because they have no aperture ring), whether that's included in the lens code or not.
- CX: Specifically designed to work with the Nikon 1 cameras.
- E: Nikon's Series E lenses are bargain-priced optics with great image quality, but less rugged mechanical innards suitable for use by non-professionals. They frequently include aluminum or plastic parts where brass is used in the most costly Nikkors. However, their lens mounts are all metal, so Series E lenses are more rugged than you might think.
- D: When a D is included in the lens name, the lens is capable of communicating focus distance information to the camera, which supposedly helps with 3-D matrix metering and flash photography.
- G: Lenses with this marking have no aperture ring. The aperture must be set by the camera, either automatically or by holding the EV/Aperture button and spinning the command dial (on the D50). The only caveat you should know is that these lenses cannot be used on older cameras that require an aperture ring.
- AF, AF-D, AF-I, AF-S: Various AF designations show that the lens is an autofocus lens. The secondary code letter provides additional information: D is a D-type lens; I focuses through an internal motor; S focuses or fine-tunes focus manually even with AF engaged.
- FX: The FX lenses are designed to work on full frame or 35mm format cameras. Apart from a few specialist lenses they will mount and operate on both full frame and APSC format sensor cameras. Early lenses with no electrical connections may only operate as manually metered and many of the later electrically connected lenses will not meter with some of the "lower end" DSLR models.
- DX: All DX lenses are designed exclusively for use with digital cameras having the 1.5x crop factor. Their coverage circle isn't officially large enough to fill up a full 35mm frame (although the 17-55mm f/2.8 DX lens actually covers the full frame well from 28-55mm). The digital only design means that these lenses can be smaller and lighter than their full-frame counterparts.
- VR: These lenses have Nikon's vibration-reduction technology, which shifts lens elements to counteract camera shake or movement, and allow taking photos without a tripod at slower shutter speeds.
- ED: The ED designation indicated that the lens has elements made of extra-low dispersion glass, which tends to reduce chromatic aberration and other defects. Some lenses use a LD (low dispersion) or UD (ultra low dispersion) marking.
- Micro: The term micro is Nikon's Designation for a macro lens.
- IF: This code means that the lens has internal focusing, so the length of the lens doesn't increas or decreas as the lens is focused.
- IX: These were produced for the Nikon's Pronea APS film cameras. Although many standard Nikkor lenses could be used on the Pronea 6i and Pronea S, the revers is not true.
- DC: The DC stands for defocus control, which is a way of changing the appearance of the out-of-focus portions of an image, especially useful for portraits or close-ups.