Technology

Acronyms, abbreviations, and terminologies used in Nikon’s NIKKOR lenses

When shopping for NIKKOR lenses, one might get confused with the acronyms used in them. I decided to do some research and come up with a quick list for each reference.

IF (Internal Focusing)

Imagine being able to focus a lens without it changing in size. Nikon’s IF technology enables just that. All internal optical movement is limited to the interior of the nonextending lens barrel. This allows for a more compact, lightweight construction as well as a closer focusing distance. In addition, a smaller and lighter focusing lens group is employed to ensure faster focusing. The IF system is featured in most NIKKOR telephoto and selected NIKKOR zoom lenses.

VR (Vibration Reduction)

This innovative VR system minimizes image blur caused by camera shake, and offers the equivalent of shooting at a shutter speed three stops (eight times) faster.* It allows handheld shooting at dusk, at night, and even in poorly lit interiors. The lens’ VR system also detects automatically when the photographer pans — no special mode is required.

* As determined by Nikon performance tests.

ED (Extra-low Dispersion)

An essential element of NIKKOR telephoto lenses, Nikon developed ED (Extra-low Dispersion) glass to enable the production of lenses that offer superior sharpness and color correction by minimizing chromatic aberration.

Put simply, chromatic aberration is a type of image and color dispersion that occurs when light rays of varying wavelengths pass through optical glass. In the past, correcting this problem for telephoto lenses required special optical elements that offer anomalous dispersion characteristics — specifically calcium fluoride crystals. However, fluorite easily cracks and is sensitive to temperature changes that can adversely affect focusing by altering the lens’ refractive index.

So Nikon designers and engineers put their heads together and came up with ED glass, which offers all the benefits, yet none of the drawbacks of calcium fluorite-based glass. With this innovation, Nikon developed several types of ED glass suitable for various They deliver stunning sharpness and contrast even at their largest apertures. In this way, NIKKOR’s ED-series lenses exemplify Nikon’s preeminence in lens innovation and performance.

RF (Rear Focusing)

With Nikon’s Rear Focusing (RF) system, all the lens elements are divided into specific lens groups, with only the rear lens group moving for focusing. This makes autofocusing operation smoother and faster.

D (Distance)

D-type and G-type NIKKOR lenses relay subject-to-camera distance information to AF Nikon camera bodies. This then makes possible advances like 3D Matrix Metering and 3D Multi-Sensor Balanced Fill-Flash.

Note: D-type and G-type NIKKOR lenses provide distance information to the following cameras: Auto exposure; F6, F5, F100, F90X, F80, F75, F70, F65, F60, F55, F50, PRONEA S, PRONEA 600i, D2 series, D1 series, D100 and D70s/D70.

Flash control; F6, F5, F100, F90X, F80, F75, F70, D2 series, D1 series, D100 and D70s/D70.

G (Gelded)

The G-type NIKKOR has no aperture ring; aperture should be selected from camera body.

DC (Defocus Control)

Unique NIKKOR lenses for unique portraits, AF DC-NIKKOR lenses feature exclusive Nikon Defocus-image Control technology. This allows photographers to control the degree of spherical aberration in the foreground or background by rotating the lens’ DC ring. This will create a rounded out-of-focus blur that is ideal for portrait photography. No other lenses in the world offer this special technique.

Automatic Indexing (AI)

AI became standard on Nikon cameras and Nikkor lenses in 1977. Non-AI lenses coupled to the camera’s meter through a system that required a pin on the camera to be mated to a slotted prong on the lens before the lens was mounted, then the aperture ring on the lens had to be turned from one extreme to the other to index the meter to the maximum aperture of the lens. AI eliminates this entire procedure because meter coupling and indexing occur automatically when the lens is mounted on the camera. Most AI lenses made until a few years ago were also supplied with the coupling prong so they would be compatible with either metering system.

Manual / Auto (M/A)

AF-S NIKKOR lenses feature Nikon’s exclusive M/A mode, that allows switching from autofocus to manual operation with virtually no time lag — even during AF servo operation and regardless of AF mode in use.

Digital Exclusive (DX)

The lens is specifically designed for use on Nikon digital SLR cameras. It produces a smaller image circle for more efficient coverage of the imaging sensor in these cameras, which is smaller than the 35mm film frame.

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