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Current Category Digital SLR Accessory > Nikon Lens > Nikon / Nikkor Lens Terminology

What is the meaning of the letters ED, IF, AI-S, AF-S, D, G, etc. used in the Nikkor lenses/ Nikon Lenses?

ED: Extra-Low Dispersion glass High-quality glass that corrects for chromatic aberration, a type of image and colour distortion that occurs when light rays of varying wavelengths pass through optical glass and don't converge or focus at the same point. Nikkor lenses with ED glass deliver superior sharpness and contrast, even at maximum aperture. Super ED glass is a new type that is used together with ED glass in some lenses to achieve an even higher degree of freedom from chromatic aberration.

D: Distance D-type AF-Nikkor lenses relay subject-to-camera distance information to Nikon SLR cameras that feature 3D Colour Matrix Metering, 3D Matrix Metering, and 3D Multi-Sensor Balanced Fill-Flash.

G: The lens has no aperture control ring and is designed to be used with cameras that allow setting the aperture from the camera body. G lenses also provide Distance information to the camera.

AI-P: A manual-focus Nikkor lens with a built-in CPU which transfers data from the lens to the camera's metering systems.

IF: Internal Focus Focus is accomplished without the lens barrel rotating or changing length, an advantage when using a position-sensitive filter such as a polarizer or split neutral-density.

AF-S: Autofocus Silent Focusing is driven by a "Silent Wave" motor in the lens instead of the focus drive motor in the camera. AF-S lenses focus faster than standard AF-Nikkors and almost completely silently. AF-S lenses with a "II" designation weigh less and are generally smaller than their equivalent predecessors.

DC: Defocus Control A lens which allows the photographer 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. With the DC control set at zero, a DC-Nikkor lens operates in the same way as a non-DC lens with the same focal length and maximum aperture.

CRC: Close Range Correction Improves image quality at close focusing distances. The lens elements are configured in a "floating element" design wherein each lens group moves independently to achieve focusing. This ensures superior lens performance even when shooting at close distances.

PC: Perspective Control A lens whose axis can be shifted laterally relative to the film plane, allowing the camera to be repositioned to reduce the convergence of vertical lines in architectural photography.

ASP: Aspherical lens elements Aspherical lenses minimize coma and other types of lens aberrations, even when used at the widest aperture. They are particularly useful in correcting distortion in wide-angle lenses and help contribute to a lighter, more compact design by reducing the number of standard (spherical) elements necessary.

RF: Rear Focusing A focusing system in which only the rear lens group moves to achieve focus. This design technique makes autofocusing operation smoother and faster.

VR: Vibration Reduction An optical innovation that minimizes image blur caused by camera shake and offers the equivalent of shooting at a shutter speed three stops faster, allowing sharper handheld pictures with longer lenses. The system even automatically detects when a photographer pans while photographing a moving subject. VR operation is available only with specific Nikon cameras.

M/A: A focusing mode on some AF-Nikkor lenses which allows switching from automatic to manual focusing with virtually no lag time by simply turning the focusing ring on the lens.

AI: Automatic Indexing 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.

AI-S: Automatic Indexing (modified) AI-S coupling is a refinement of AI and became standard in 1982. The diaphragm action in an AI-S lens is compatible with Nikon cameras that allow the aperture to be controlled from the camera, as is required for programmed and shutter-priority automatic exposure control. All AF-Nikkor lenses, as well as most manual-focus Nikkor lenses made since 1982, are AI-S.

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.

What is the meaning of the different designations/codes on Nikon/Nikkor auto-focus lenses?

AF
These were the first generation of Nikon AF lenses. All Nikon auto-focus SLR cameras are compatible with Nikon AF lenses which contain a CPU (central processing unit). These lenses are easy to recognise as the letters 'AF' can be is identified on the lens and they have CPU contacts on the rear of the lens as shown in the image below.

Early Nikon camera bodies which employ AF technology support basic auto-focus but later cameras manufactured since 1996 with advanced metering systems require D (distance) information for exposure metering (see AF-D below). Cameras that support advanced 3D Matrix Metering require distance information to be transmitted from the lens, if a standard AF lens is used, an abridged version of the metering system will be employed.

AF-D
Nikon introduced AF-D series lenses in 1996, while these lenses look similar to AF lenses they contained an encoding microchip that transmits focusing distance information to the camera body, this information is used to enhance the accuracy of the cameras exposure and flash metering systems. Cameras with advanced 3D matrix metering systems require AF-D compatible lenses to take full advantage of this technology. All current Nikon auto-focus lenses transmit distance information to compatible cameras and are therefore AF-D compatible, AF-D lenses are recognised by the D designation marked on the lens as illustrated in the image below.

AF-G
AF-G lenses where introduced in 2000, these lenses are similar to AF-D lenses and offer the same functionality as AF-D lenses but do not feature an aperture ring. (an aperture ring is only required by older Nikon SLR cameras which can't detect this information from the lens).

AF-S (AF-I)
Nikon AF-S lenses and it's predecessor AF-I offer the same functionality as AF-D or AF-G lenses. The difference between these lenses is that AF-S / AF-I lenses contain a focusing motor built into the lens, rather than using the auto focus motor built into the camera body. This system enables faster focusing and in the case of the AF-S lenses near silent auto focusing.

DX
Nikon announced the introduction of DX lenses in 2002 incorporating technology from earlier lens types but offering better performance for Digital SLR users. DX lenses produce a small image circle which does not cover the 135 film area, therefore they are not recommended for use with film SLR cameras as cropping may occur. Their advanced design enables high quality optics and extended zoom ranges to be incorporated into compact lenses designs.

What do the terms ED-IF, VR, DX, AF-S, etc. in Nikon/Nikkor lens mean?

ED - The lens uses Extra-low Dispersion glass for superior image quality, especially at wide apertures.

IF - Internal Focus, focus is accomplished without the lens barrel rotating or changing length, an advantage when using a position-sensitive filter such as a polarizer.

AF-S - Focusing is driven by a "Silent Wave" motor in the lens instead of the focus drive motor in the camera. AF-S lenses focus faster than standard AF-Nikkors and are almost completely silent. AF-S lenses with a "II" designation weigh less and are generally smaller than their equivalent predecessors.

D - The lens provides Distance information to the camera electronically for more accurate light metering.

G - The lens has no aperture control ring and is designed to be used with cameras that allow setting the aperture from the camera body. G lenses also provide Distance information to the camera.

DC - Defocus Control, the optical characteristics of the lens can be altered to change the appearance of the out-of-focus elements in the background or foreground.

VR - Vibration Reduction, lenses with this feature can be hand-held at lower shutter speeds than non-VR lenses because they have a system that detects and counteracts vibration associated with hand-holding a camera and lens. (VR operation is available only with specific Nikon cameras.)

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

Note: The above information is from Nikon Australia for your reference to understand Nikon/Nikkor Lenses, please refer to Nikon Australia Web Site for more details.