The Nikon F-mount is a type of interchangeable lens mount developed by Nikon for its 35mm format single-lens reflex cameras. The F-mount was first introduced on the Nikon F camera in 1959, and features a three-lug bayonet mount with a 44mm throat and a flange to focal plane distance of 46.5mm. The company continues, with the 2020 D6 model, to use variations of the same lens mount specification for its film and digital SLR cameras.
The Nikon F-mount successor is the Nikon Z-mount. The FTZ II (and the original FTZ) lens adapter allows many F-mount lenses to be used on Z-mount cameras.
History The Nikon F-mount is one of only two SLR lens mounts (the other being the Pentax K-mount) which were not abandoned by their associated manufacturer upon the introduction of autofocus, but rather extended to meet new requirements related to metering, autofocus, and aperture control. The large variety of F-mount compatible lenses makes it the largest system of interchangeable flange-mount photographic lenses in history. Over 400 different Nikkor lenses are compatible with the system. The F-mount is also popular in scientific and industrial applications, most notably machine vision. The F-mount has been in production for over years, the only SLR lens mount with such longevity.
Design
System of lenses In addition to Nikon's own range of "Nikkor" lenses, brands of F-mount photographic lenses include Zeiss, Voigtländer, Schneider, Angénieux, Samyang, Sigma, Tokina, Tamron, Hartblei, Kiev-Arsenal, Lensbaby, and Vivitar. F-mount cameras include current models from Nikon, Fujifilm, Sinar, JVC, Kenko and Horseman. Numerous other manufacturers employ the F-mount in non-photographic imaging applications.
Compatibility The F-mount has a significant degree of both backward and forward compatibility. Many current autofocus F-mount lenses can be used on the original Nikon F, and the earliest manual-focus F-mount lenses of the 1960s and early 1970s can, with some modification, still be used to their fullest on all professional-class Nikon cameras. Incompatibilities do exist, however, and adventurous F-mount users should consult product documentation in order to avoid problems. For example, many electronic camera bodies cannot meter without a CPU enabled lens; the aperture of G designated lenses cannot be controlled without an electronic camera body; non-AI lenses (manufactured prior to 1977) can cause mechanical damage to later model bodies unless they are modified to meet the AI specification; and AF-P lenses (introduced in 2016) will not focus, even manually, on cameras introduced before roughly 2013. Many manual focus lenses can be converted to allow metering with consumer Nikon bodies by adding a Dandelion chip to the lens.
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Most Nikon F-mount lenses cover a minimum of the standard 36×24mm area of 35mm format and the Nikon FX format, while DX designated lenses cover the 24×16mm area of the Nikon DX format, and industrial F-mount lenses have varying coverage. DX lenses may produce vignetting when used on film and FX cameras. However, Nikon lenses designed for film cameras will work on Nikon digital system cameras with the limitations noted above.
Mounting and control rings F-mount lenses lock by turning counter-clockwise (when looking at the front of lens) and unlock clockwise. Nearly all F-mount lenses have zoom and focus controls that rotate in the clockwise direction (as viewed from behind the camera) to increase focal length and focus distance respectively. This convention is also used in Pentax K-mount and Sony A-mount lenses but is opposite of the direction normally used by Canon. F-mount lenses also typically have aperture rings that turn clockwise to close. The aperture rings have two sets of f-stop numbers. On cameras equipped with Nikon's Aperture Direct Readout (ADR) system, a small window under the pentaprism reads the smaller scale and displays the selected f-stop in the viewfinder.
Nikkor Designations Nikon has introduced many proprietary designations for F-mount Nikkor lenses, reflecting design variations and developments both in lenses and the F-mount itself. There are also "unofficial" designations used by collectors and dealers to differentiate similar lenses.
Pre-autofocus There are four major generations of manual-focus Nikkor lens styles, which may be distinguished cosmetically and functionally: +Manual-focus Nikkor lenses Name AKA Example Cosmetics Body will meter at full aperture Focus ring Meter coupling Aperture scale NAI AI AI-S A F, C, Auto, NAI F-type ("Pre-AI") lens: Nikkor 50mm 1:1.4. Scalloped metal Solid prong, triangular or semicircular Single row of values, multicolored rowspan=2 rowspan=2 colspan=2 (stop-down) K RIFR K-type lens: Fisheye-Nikkor 16mm 1:3.5. Rubber inset, diamond or waffle pattern AI AI lens: Nikkor 135mm 1:2.8; note multicolored aperture values corresponding to the depth of field scale. Rubber inset, waffle pattern Cutaway semicircular prong + ridge Doubled, large multicolored values and small ADR values in white only colspan=2 AI-S AI-S lens: Nikkor 50mm 1:1.4; note the smallest aperture value () is colored orange on both scales. Doubled, smallest value in orange on both regular and ADR scales colspan=3
A — Auto Nikkor (also unofficially F, Pre-AI, Non-AI or NAI), introduced in 1959 Designation for the first generation of F-mount lenses, introduced in 1959. These were all single-coated, and meter coupling was provided by a prong (known as the Meter Coupling Prong) fixed to the lens's aperture ring. The Photomic T through-the-lens light meter introduced in 1965 worked at full aperture, so the maximum aperture of the lens had to be communicated to the meter via a manual setting on the ASA dial. The Nikkormat FTn and FTn metered finder for the Nikon F introduced semi-automatic aperture indexing which was achieved by mounting the lens with the aperture ring set to 5.6, and then turning the ring to first the minimum and then the maximum apertures. (The need for this step was eliminated by the AI system below.) Early versions are marked "Nippon Kogaku Japan" and have their focal lengths stated in centimetres, but models produced after about 1965 have focal lengths stated in millimetres. The "Nippon Kogaku Japan" engraving was replaced by "Nikon" from 1971 onwards.Mounting a non-AI lens can damage many modern Nikon camera bodies. AI-cameras that still may use non-AI lenses includes the Nikon F2A/F2AS with Photomic A (DP-11) or AS (DP-12) finder, Nikon (Nikkormat) EL2, as well as Nikon FM and FE. In addition, the Nikon Df, a DSLR introduced in late 2013, can use non-AI lenses. The A lenses can be converted to the AI specification; see AI'd below. T, Q, P, H, S, O, N, UD, QD, PD — Appears immediately before or after the "Nikkor" name on F-type lenses (see above), designating the number of optical elements in the design. Short for Tres (3), Quattuor (4), Penta (5), Hex (6), Septem (7), Octo (8), Novem (9), UnDecim (11), QuattuorDecim (14) and Penta-Decem (15). The terms Unus (1) and Bini (2) were also apparently designated, but never used. Terms P=Penta, H=Hexa, and PD=Penta-Decem (Greek root) were used (instead of Quinque, Sex, and QuinDecim) to avoid ambiguity with Quattuor, Septem and QuattuorDecim. This designation scheme was dropped with the introduction of "Modern" (K-type) Nikkors in 1974. Auto — Designation for F-type lenses indicating an automatic diaphragm (aperture). Not to be confused with automatic exposure or auto focus, the designation fell out of use in the early 1970s and was not carried onto K-type lenses. C — Indicates a multicoated F-type lens. Appears with an interpunct after the number of optical elements (in the form "Nikkor-X·C"). This designation was introduced in 1971 and discontinued in 1974 with the introduction of "Modern" (K-type) Nikkors, when multicoating had become standard practice.
K — "Modern" or "New" Nikkors introduced in 1974 While Pre-AI for compatibility purposes, K-type lenses introduced the new cosmetics that would be used from 1977 onwards for AI-type lenses (see below). The scalloped-metal focus rings were replaced with rubber grip insets, and the use of element number and coating designations was discontinued. The 'K' designation itself is believed to be derived from the Japanese "konnichi-teki", loosely translatable as "modern" or "contemporary".
AI — Manual focus with "Automatic Maximum-Aperture Indexing," introduced in 1977 The AI standard adds a Meter Coupling Ridge to the aperture ring, which encodes the current aperture setting relative to the maximum, and a Lens Speed Indexing Post on the mounting flange, which encodes the maximum aperture itself. The Ridge and Post couple to the camera's light meter. Lenses designated AI-S, Series E, and AF all include these features of AI. Current professional Nikon camera bodies link with the Meter Coupling Ridge, but the Lens Speed Indexing Post is ignored and the maximum aperture value is set electronically by the operator instead. AI-designated lenses also improved on the original Meter Coupling Prong, adding cutaways which allow more ambient light to fall on the aperture ring, increasing visibility on cameras which optically projected the setting inside the viewfinder. AI'd — An unofficial designation for lenses converted partially (Meter Coupling Ridge only) or completely from non-AI to AI. This is accomplished by replacing the aperture ring and the metering prong (using a long-discontinued kit procured from Nikon, also known as a factory conversion) or by modifying the original part. A conversion is also possible by taking a grinder to the meter coupling ridge. One can find such hacked lenses in the used marked quite often. For collectors of classic lenses, such hacks are undesirable and considered to be damaged lenses although they function normally if the hack is performed correctly. Some independent camera repair technicians continue to offer these conversions. The factory conversion kit included a new set of coupling prongs, with holes in them. This can be easily used to identify a "factory conversion" AI'd lens.
AI-S — AI lenses with standardized aperture control, introduced in 1981 The successor to AI, the AI-S specification added two mechanical enhancements — standardized aperture control, and the Focal Length Indexing Ridge — required for the shutter priority and other auto-aperture exposure modes of the Nikon FA, F-301/N2000, and F-501/N2020 cameras (although the FA will operate correctly in shutter priority and program modes with any AI lens). Later cameras did not require these features, and interoperate with AI and AI-S lenses identically. The term AI-S is now commonly used to refer to manual focus lenses, and Nikon continues to produce eight prime lens models in its AI-S line. All Nikon AF lenses with aperture rings (non-G) also meet the AI-S specification, except for their lack of a Meter Coupling Prong (which can be added). Visually, AI-S lenses can quickly be identified by the smallest aperture setting (usually f/22) being marked in orange, Standardized aperture control. AI-S lens apertures move in a standardized fashion in relation to their stop-down levers. The levers of AI and pre-AI lenses were intended only to close the aperture to its manual setting. The advance of aperture control by the camera body itself, by partial actuation of the stop-down lever, meant more precision was required for consistent exposure. This feature is indicated by a Lens Type Signal notch in the lens mount. Note that despite popular misconception, the F4 is NOT capable of engaging P and S auto-exposure modes with non-CPU lenses Focal Length Indexing Ridge. AI-S lenses with a focal length of 135mm or longer are indicated by a ridge on the lens mount, used by FA and F-501 to engage high-speed-biased Program Autoexposure.
Autofocus lenses