A bayonet mount is the scientific name for a lens mount for photo and video equipment. It can be a fastening system or a special unit with which the lens is mounted on the camera. Leading companies producing cameras have developed their own mount standards, so the mount of one company is often incompatible with another. However, there are standardized systems and additional devices (for example, an adapter-bayonet) that allow you to install optics from different companies. The most common mount types are Nikon F, Canon EF, and Sony E.
Bayonet F of the Nikon company
With the development of photography, it became clear that full-time optics, tightly connected to the body of the device, are not able to satisfy the creative ideas of professionals. The solution was found in the use of interchangeable lenses. Nikon was one of the first to introduce a standard for fixing removable lenses. The mount type introduced by Nikon in 1959 is a detachable bayonet mount used to connect a 35 mm camera (body) and lens.
Lenses with the original F-mount system were used extensively until 1977, until an AI-compatible element appeared. Even modern Nikon lenses can be used with a type F device and work fine with older cameras, although mounting may require minor mechanical modifications.
Operating principle
A bayonet mount is a fairly simple device. In order to connect a type F lens to the camera, you need to manually align the protrusion on the lens with the antenna bar of the exposure metering system, which was fixed at f / 5.6 aperture. Later, lenses of this type were also called pre-AI or non-AI.
Compatibility
Nikon F mount lenses work perfectly with all modern Nikon cameras at least in manual exposure mode, especially if you refine them for compatibility with AI mount. In this case, the operation of the aperture priority modes will depend on the camera model. Matrix exposure metering requires a special modernization of the bayonet mount, so it usually does not work with such lenses, even if they are modified to the AI standard.
Design features
Starting with lenses equipped with a Nikon F mount system, the company used a jumping aperture mechanism. That is, this part is constantly open when hovering over the sharpness and closes only a moment before the moment of photographing. Due to this, the image in the viewfinder does not darken and does not make it difficult to point, even if the aperture ring is moved to the closed position. Structurally, this is implemented as a lever built into the camera's socket, which is lowered before taking a picture. Another lever is released in the lens, which, under the action of a spring, closes the diaphragm blades.
Nikon Type AI Mount
AI (Automatic Indexing) - an improved version of the first Nikon F mount - was proposed in 1977. Fans of Nikon products were waiting for an updated system that allowed them to quickly change optics. Sometimes a masterpiece is separated from a mediocre photo by several lost seconds, wasted on replacing the lens. And the photo giant introduced a new bayonet mount. This is a modernized design that allowed you to put the lens with one movement of the hand and not waste time getting the aperture ring into the index antenna.
When used on modern cameras, AI lenses can work in modes such as manual (M) and aperture priority (A) with exposure metering pointwise or in the center. Some cameras may also use matrix metering.
The lenses of the old type (F) are very easy to refine to AI by increasing the performance, which, touching the lever in the camera mount, reports the position of the aperture ring.
Innovations
It was expected that the main innovation would be the establishment of mechanical levers that should inform the camera about the focal length of the lens. Experts suggested that the new Nikon cameras would somehow use this information. But this did not concern the upgraded bayonet mount. Designers went the other way: modern lenses transmit the necessary information electronically. This method turned out to be much cheaper and more reliable. AI-lenses are now sold for nothing, although they are not much inferior to modern AI-S (for example, they do not have a quick program mode).
Soviet and Ukrainian cameras and lenses
On the territory of the USSR and Ukraine, 35 mm cameras and lenses compatible with the Nikon AI mount were produced by the Arsenal factory in Kiev. Among the cameras were the following:
- "Kiev-17";
- "Kiev-20";
- "Kiev-19";
- "Kiev-19M";
- Arsat line of lenses.
Nikon AI-s mount
This is the next evolutionary stage for removable lenses. Such a device is used today. It can be easily cast from AI by a specific rounded cut-out on a bayonet mount, which is available on the chrome ring scale of depth of field (in AI the surface is black), marked with orange paint to indicate the minimum aperture.
The letter "S" means that the aperture closing coefficient linearly affects the deviation of the diaphragm indicator lever in the bayonet mount. Thanks to the innovation in cameras with autofocus, the accuracy of aperture measurement has significantly improved. For manual models, this improvement is not relevant.
Compatibility with previous types
- All AI-S lenses are compatible with AI lenses.
- All AF, AF-I and AF-S lenses are also compatible with the AI-S mount system.
- All AI-S lenses operate on Nikon DSLRs at least in manual mode.
- Most Nikon SLR cameras, including digital ones, can operate in aperture priority mode, except for a number of amateur-level devices.
Before planning a purchase, read the camera’s user manual, which always provides support information for specific types of lenses.
Type P mount
This hybrid standard was introduced in 1988 specifically for telephoto handheld lenses, which were supposed to hold Nikon's position until telephoto AF lenses became widespread. At that time, the best “autofocusers” were models with 300 mm f / 2 8 parameters.
Nikon has released few P-type lenses. Among them are 500mm f / 4 P (1988); 1200-1700 mm f / 5.6-8.0 P ED; 45mm f / 2.8 P.
Type P lenses are AI-S manual with a few electronic AF mount contacts added. This approach made it possible to use the matrix metering mode, which only appeared on autofocus cameras.
AF mount
AF Nikon autofocus lenses (except AF-I and AF-S) are sharpened by the rotation of the engine in the camera, which is transmitted through a special mechanism to a removable lens. Photographers called this mechanism a "screwdriver." Now this system looks primitive in comparison with the autofocus Canon system, but this design allowed in the distant 1980 to maintain full compatibility with non-autofocus lenses. All autofocus devices (including AI-S) work great on non-autofocus cameras. However, devices that do not support AI, still require refinement.
AF-N mount
The designation AF-N was introduced only to distinguish AF lenses from older series from newer ones. After the release of the first AF lenses, Nikon decided that with such a convenient technology, no one else would take pictures in manual mode. Therefore, the first AF-lenses were equipped with a thin inconvenient manual focus ring, which was almost impossible to use. However, it turned out that photographers prefer the good old wide rubberized focus rings. Therefore, the engineers returned them back to autofocus lenses and called the new AF-N modifications. Modern lenses are equipped with convenient focus rings, so the AF-N designation no longer applies to them.
AF-D mount
Lenses of this category inform the “intelligence” of the camera about the distance they are focused. Theoretically, in specific situations, this should help the matrix metering system determine the exposure more accurately, especially when using the flash. But in practice, the AF-D mount has more marketing value than practical. Moreover, the presence of AF-D may even cause incorrect exposure determination if the flash and the sensor (film) are at different distances from the subject.
Focus speed has nothing to do with the presence or absence of AF-D mount support. It's just that these are newer lenses, so they function faster than their predecessors. All AF-D lenses, just like AF and AI-S, work great on non-autofocus cameras.
Canon ef
Bayonet is not an exclusive Nikon concept. Other companies have also developed their interchangeable lens mount systems. The eternal competitor - Canon - is also famous for its thoughtful types of mount designs. While Nikon was promoting AI-S, Canon introduced the excellent EF mount.
Canon mount first appeared on the EOS 650 in 1987, when the company launched a series of autofocus SLR cameras. This element differed from analogues, first of all, by the presence of electrical contacts, through which control information was transmitted to the lens. At the same time, in the EF mount, they refused mechanical control of the diaphragm, autofocus drive, and some other properties. Much later, a similar control option was used by Olympus in the Four-Thirds system.
Canon EF-S
The EF-S variant provides a short length from the rear lens to the image sensor. It is partially compliant with the EF standard, since lenses with an EF mount can be used in cameras with an EF mount and EF-S.
Sony E-mount
The E-mount is a Sony-branded mount for lenses for Alpha NEX series mirrorless cameras and NXCAM camcorders. This is a fairly recent development, introduced in 2010 and implemented for the first time in the products of the Sony α series (NEX-3, -5 cameras). A feature of the E-mount system connection is a ten-pin digital interface.
The bayonet mount with index “E” is used in mirrorless compact cameras equipped with matrices that provide image quality at the level of “DSLRs”. At the same time, Sony engineers use A mount for SLR cameras with advanced interchangeable lenses with a system of translucent mirrors. Two systems in addition to some design features differ in the size of the working segment. This is the distance from the focal plane (matrix) to the end of the lens. In mirror cameras, the matrix and the lens are separated by a mirror, so the working length is large, the physical size of the interchangeable optics increases. For the E-mount, a mirror is not required, so lenses are much lighter and more compact.
Compatibility with products of other manufacturers
Surprisingly, Japanese designers did not go their own way, but chose an openness strategy. The features of such a development as the Sony E bayonet mount allow producing specialized adapters connecting the lens with almost any modern mount from the following companies:
- Pentax;
- Olympus
- Nikon
- Leica
- Hasselblad;
- Exakta;
- Minolta AF;
- Canon EF;
- Contarex
- Contax
- Rollei
- Micro 4: 3;
- Threaded T-mount, type C, M39 × 1, M42 × 1 and others.
In 2011, the company discovered the features of such a device as the Sony mount, which allows third-party companies to produce their own lenses for Japanese cameras.
Conclusion
At first glance, the mount is not a technically complex design. However, this node performs several important functions. It allows you to change the types of lenses depending on the tasks performed, and the more thoughtful the design, the faster and more convenient the replacement of optics. The second important task is the transmission of digital information in modern cameras through electrical contacts on the lens and mount, which allows the lens and camera to synchronize to obtain the highest quality pictures and video frames.