# Lens mount

A lens mount is an interface – mechanical and often also electrical – between a photographic camera body and a lens. It is a feature of camera systems where the body allows interchangeable lenses, most usually the rangefinder camera, single lens reflex type, single lens mirrorless type or any movie camera of 16 mm or higher gauge. Lens mounts are also used to connect optical components in instrumentation that may not involve a camera, such as the modular components used in optical laboratory prototyping which join via C-mount or T-mount elements.

## Mount types

A lens mount may be a screw-threaded type, a bayonet-type, or a breech-lock (friction lock) type. Modern still camera lens mounts are of the bayonet type, because the bayonet mechanism precisely aligns mechanical and electrical features between lens and body. Screw-threaded mounts are fragile and do not align the lens in a reliable rotational position, yet types such as the C-mount interface are still widely in use for other applications like video cameras and optical instrumentation.
Bayonet mounts generally have a number of tabs (often three) around the base of the lens, which fit into appropriately sized recesses in the lens mounting plate on the front of the camera. The tabs are often "keyed" in some way to ensure that the lens is inserted in only one orientation, often by making one tab a different size. Once inserted the lens is fastened by turning it a small amount. It is then locked in place by a spring-loaded pin, which can be operated to remove the lens.
Lens mounts of competing manufacturers (Sony, Nikon, Canon, Contax/Yashica, Pentax, etc.) are almost always incompatible. In addition to the mechanical and electrical interface variations, the flange focal distance from the lens mount to the film or sensor can also be different. Many allege that these incompatibilities are due to the desire of manufacturers to "lock in" consumers to their brand.
In movie cameras, the two most popular mounts in current usage on professional digital cinematography cameras are Arri's PL-mount and Panavision's PV-mount. The PL-Mount is used both on Arri and RED digital cinematography cameras, which as of 2012 are the most used cameras for films shot in digital. The Panavision mounts are exclusively used with Panavision lenses, and thus are only available on Panaflex cameras or third-party cameras "Panavised" by a Panavision rental house, whereas the PL-mount style is favored with most other cameras and cine lens manufacturers. Both of these mounts are held in place with locating pins and friction locking rings. Other mounts which are now largely historical or a minority in relation to current practices are listed below.

## List of lens mounts

| Mount name | Flange focal distance | Frame size | Throat or thread diameter | Mount thread pitch | Mount type | Primary use | Camera lines |
| Kinor 16SP | 52 mm | 16 mm | 43 mm | | Breech lock | Cinematography | Kinor 16SP, Krasnogorsk-1, -2, -3 16mm movie cameras |
| Kinor 16SX | 52 mm | 16 mm | 43 mm | | Breech lock | Cinematography | Kinor 16SX-1M,-2M 16mm movie camera |
| OST/OCT-19 | 68 mm | 35 mm | 61 mm | | Breech lock | Cinematography | Konvas-2M, Kinor-35H 35mm movie cameras |
| Kiev-16U | 31 mm | 16 mm | 32 mm | 0.5 mm | Screw | Cinematography | Kiev-16U/UE 16mm movie cameras |
| Kiev-16C | 17.35 mm | 16 mm | 27 mm | 0.75mm | Screw | | Kiev-1C 16mm movie camera |
| Canon SV | 32.00 mm | | | | Bayonet | Photography (Digital) | Canon RC-701 & 760 |
| Argus C3 | 40.3 mm | 35 mm | 34 mm | 20 TPI | Screw | Photography | Argus C3 |
| Canon EX | 20 mm | 1/2" | | | Bayonet | Photography | |
| Canon FL | 42 mm | 35 mm | 48 mm | | Breech lock | Photography | |
| Canon FD | 42 mm | 35 mm | 48 mm | | Breech lock | Photography | Canon F series, A series, and T series SLRs |
| Canon FDn (a.k.a. "New FD") | 42 mm | 35 mm | 48 mm | | Bayonet | Photography | completely interchangeable with earlier FD lenses |
| Canon EF | 44.00 mm | 35 mm | 54 mm | | Bayonet | Photography | Canon EOS 35mm film SLR, Full Frame & APS-H DSLR |
| Canon EF-S | 44.00 mm | APS-C | 54 mm | | Bayonet | Photography (Digital) | Canon EOS APS-C DSLR |
| Canon EF-M | 18 mm | APS-C | 47 mm | | Bayonet | Photography (Digital) | Canon EOS M series Mirrorless APS-C Cameras |
| Canon RF | 20 mm | 35 mm and APS-C | 54 mm | | Bayonet | Photography (Digital) | Canon EOS R series full-frame and APS-C mirrorless cameras; lenses designated as RF-S are optimized for APS-C sensors, but will mount on full-frame bodies |
| Nikon S | 34.85 mm | 35 mm | 34 mm | | Bayonet | Photography | Nikon Rangefinder |
| Nikon F | 46.5 mm | 35 mm | 44 mm | | Bayonet | Photography | Nikon F 35mm film SLR, Full Frame & APS-C DSLR |
| Nikon 1 | 17 mm | 13.2 x 8.8mm | 40 mm | | Bayonet | Photography (Digital) | Nikon 1 series |
| Nikon Z | 16 mm | 35 mm | 55 mm | | Bayonet | Photography (Digital) | Nikon Z - Mirrorless Full Frame & APS-C |
| Sony Mavica | 57 mm | | | | Bayonet | Photography (Digital) | |
| Sony E | FE | 18 mm | 35 mm and APS-C | 46.1 mm (1.815 inch) | | Bayonet | Photography (Digital) | Sony E/FE Mount Alpha Mirrorless Full Frame / APS-C| Sony NEX Mirrorless APS-C |
| Minolta SR | 43.50 mm | 35 mm | 44.97 mm | | Bayonet (54°) | Photography | Minolta SR/MC/MD |
| Minolta V | 38.00 mm | APS-H | 39.7 mm | | Bayonet | Photography | Minolta Vectis |
| Minolta A | 44.50 mm | 35 mm and APS-C | 49.7 mm (1.939 inch) | | Bayonet (54°) | Photography | Minolta DSLR AF/Alpha/Dynax/Maxxum Sony DSLR Alpha (α) A Mount |
| Pentax Auto 110 | 27 mm | 110 film | 19.5 mm | | Bayonet | Photography | Pentax Auto 110 and Auto 110 Super |
| Pentax Q | 9.2 mm | 1/2.3", 1/1.7" | 31 mm | | Bayonet | Photography (Digital) | |
| Pentax K | 45.46 mm | 35 mm and APS-C | 44 mm | | Bayonet | Photography | Used also by Ricoh, Chinon, Agfa, Vivitar and KMZ Zenit cameras |
| Leitz Visoflex I | 91.3 mm | 35 mm | M39 | 26 TPI | Screw | Photography | |
| Leitz Visoflex II/III | 67.8 mm | 35 mm | 44 mm | | Bayonet (Leica M) | Photography | |
| Leica M | 27.80 mm | 35 mm | 44 mm | | Bayonet | Photography | Leica M series Leica CL Minolta CLE |
| Leica R | 47.00 mm | 35 mm | 49 mm | | Bayonet | Photography | |
| Leica L | 20 mm | 35 mm and APS-C | 51.6 mm | | Bayonet | Photography (Digital) | L-Mount Alliance (Leica, Panasonic, Sigma, DJI and Blackmagic Design cameras) |
| Contax RF | 34.85 mm | 35 mm | 44 mm | | Double bayonet | Photography | Contax I, II, III, IIa, IIIa Kiev rangefinders |
| Contax G | 29.00 mm | 35 mm | 44 mm | | Breech lock | Photography | |
| Contax N | 48 mm | 35 mm | 55 mm | | Bayonet | Photography | |
| Contax/Yashica | 45.5 mm | 35 mm | 48 mm | | Bayonet | Photography | Yashica/Contax |
| Yashica MA | ~45.8 mm | 35 mm | | | Bayonet | Photography | Kyocera Yashica 230 AF etc. |
| Fujica X | 43.5 mm | 35 mm | 49 mm | | Bayonet | Photography | Fujica-X |
| Fujifilm X | 17.7 mm | APS-C | 44 mm | | Bayonet | Photography (Digital) | Fujifilm X series mirrorless |
| Olympus Pen F | 28.95 mm | 35 mm half-frame | | | Bayonet | Photography | |
| Olympus OM | 46 mm | 35 mm | 46 mm | | Bayonet | Photography | |
| Four Thirds | 38.67 mm | 17.3 mm × 12.98 mm | ~44 mm | | Bayonet | Photography (Digital) | Olympus E Panasonic Lumix DMC-L Leica Digilux |
| Micro Four Thirds | 19.25 mm | 17.3 mm × 12.98 mm | ~38 mm | | Bayonet | Photography (Digital) | Olympus Pen & OM-D series Panasonic G, GF, GX & GH Series Blackmagic Design Cinema Camera |
| KM | 28 mm (27.80 mm?) | 35 mm | 44 mm | | Bayonet | Photography | Konica Hexar RF |
| Konica F | 40.50 mm | 35 mm | 40 mm | | Bayonet | Photography | Konica F |
| Konica AR | 40.50 mm | 35 mm | 47 mm | | Bayonet | Photography | Konica Autoreflex |
| Samsung NX mini | 6.95 mm | 1" | 38 mm | | Bayonet | photography (Digital) | |
| Samsung NX | 25.5 mm | APS-C | 42 mm | | Bayonet | Photography (Digital) | |
| Samsung Kenox | 44.5 mm | 35 mm | | | Bayonet | Photography | Manual focus only; there is only one compatible camera - Samsung Kenox GX-1/Samsung SR4000. |
| DJI DL | 16.84 mm | 35 mm and APS-C | 58 mm | | Bayonet | Photography (Digital), Cinematography | For aerial drone and gimbal use; DJI Zenmuse X7, X9 and DJI Ronin 4D X9 cameras. |
| Icarex BM | 48.00 mm | 35 mm | | | Breech lock | Photography | Icarex 35S |
| D | 12.29 mm | 8 mm | 15.88 mm (0.625 inch) | 32 TPI | Screw | Cinematography | |
| CS | 12.526 mm | 1/3", 1/2" | 25.40 mm (1 inch) | 32 TPI | Screw | Cinematography / Industrial | |
| C | 17.526 mm (0.69 inches) | 1/2", 16 mm, 2/3", 1" | 25.40 mm (1 inch) | 32 TPI | Screw | Cinematography / Industrial / Machine Vision | |
| S (a.k.a. M12) | N/A. Screw mount must be adjusted manually for back focus. Back focal distance from <1mm to 12mm. | 1/6" to 1" | 12 mm | 0.5 mm pitch | Screw | CCTV, PCB | Edmund Optics μ-Video |
| Bolex Bajonet | 23.22 mm | 16 mm | | | Breech lock | Cinematography | effective focal distance 17.526 mm (0.69 inches) due to beam splitter behind mount flange (accepts C-mount lenses with adapter) |
| 1/3" bayonet mount | 25 mm | 1/3" (5.24x2.94) | | | Bayonet | Video | JVC professional video cameras |
| M39 (a.k.a. L-Mount, LTM) | 28.80 mm | 35 mm | M39 | 26 TPI | Screw | Photography | Leica M39 screw mount |
| Narciss | 28.8 mm | 16 mm | M24 | 1 mm | Screw | Photography | |
| 1/2" bayonet mount | 37.80 mm | 1/2" (6.97x3.92) | | | Bayonet | Video | Non-Sony professional video cameras |
| Alpa | 37.80 mm | 35 mm | 42 mm | | Bayonet | Photography | |
| Sony 1/2" Video | 38 mm | 1/2" (6.97x3.92) | | | Bayonet | Video | Sony professional video cameras |
| Aaton universal | 40 mm | 16 mm | 50 mm | | Breech lock | Cinematography | |
| Miranda bayonet/M44 | 41.5 mm | 35 mm and APS-C | | | Bayonet | Photography | Miranda Camera Company |
| Petriflex | 43.5 mm | 35 mm | | | Breech lock | Photography | |
| Sigma SA | 44.00 mm | 35 mm | 44 mm | | Bayonet | Photography | Sigma SA |
| Paxette | 44 mm | 35 mm | M39 | 1 mm | Screw | Photography | |
| Praktiflex | 44 mm | 35 mm | M40 | 1 mm | Screw | Photography | |
| Praktica | 44.40 mm | 35 mm | 42 mm | | Bayonet | Photography | |
| Exakta, Topcon RE | 44.7 mm | 35 mm | 46 mm | | Bayonet | Photography | |
| Zenit M39 | 45.2 mm | 35 mm | M39 | 1 mm | Screw | Photography | |
| M37 | 45.46 mm | 35 mm | 37 mm | 1 mm | Screw | Photography | Asahiflex |
| M42 | 45.46 mm | 35 mm | 42 mm | 1 mm | Screw | Photography | Praktica, Pentax, Zenit |
| B4-mount | 48 mm | 2/3" (9.6x5.4) | | | Bayonet | Video | Professional and broadcast video cameras |
| Praktina | 50 mm | 35 mm | 46 mm | | Breech lock | Photography | |
| T-Thread (Very earliest type) | 50.7 mm | 35 mm | M37 | 0.75mm | Screw | Photography | Tamron |
| Adapt-A-Matic | 50.7 mm | 35 mm | 54 mm | | Bayonet | Photography | Tamron |
| Adaptall & Adaptall-2 | 50.7 mm | 35 mm | 54 mm | | Bayonet | Photography | Tamron |
| Arri standard | 52 mm | 35 mm and 16 mm | 64 mm | | Tab lock | Cinematography | |
| Arri bayonet | 52 mm | 35 mm and 16 mm | 64 mm | | Bayonet | Cinematography | |
| Arri PL | 52 mm | 35 mm and 16 mm | 54 mm | | Breech lock | Cinematography | |
| Arri LPL | 44 mm | Arri LF | 62 mm | | Breech lock | Cinematography | |
| Arri Maxi PL | 52 mm | 70 mm | 64 mm | | | Cinematography | |
| T | 55 mm | 35 mm | 42 mm | 0.75 mm | Screw | Photography | Tamron |
| YS Auto T-Thread | 55 mm | 35 mm | 42 mm | 0.75 mm | Screw | Photography | Sigma Corporation |
| T-thread | 55 mm | 35 mm | 47 mm | 0.75 mm | Screw | Photography | Tokina |
| H-Mount | 55 mm | 35 mm | 47 mm | 0.75 mm | Screw | Photography | Hanimex (rebranding of Tokina M47) |
| Panavision PV | 57.15 mm | 35 mm | 49.5 mm | | Breech lock | Cinematography | |
| B3-mount | 58 mm | 2/3" | | | Reverse bayonet | Video | Ikegami |
| Mitchell BNCR | 61.468 mm | 35 mm | 68 mm | | Breech lock | Cinematography | |
| Zeiss Panflex 5522/23 for Contax RF | 64.50 mm | 35 mm | | | Double bayonet | Photography | |
| Kowa Six/Super 66 | 79 mm | 6×6 | | | Breech lock | Photography | |
| Hasselblad | 74.9 mm | 6×6 | 69 mm | | Bayonet | Photography | |
| Hasselblad Xpan | 34.27 mm | 35 mm panoramic | 46 mm | | Bayonet | Photography | |
| Bronica ETR | 69 mm | 6×4.5 | | | Bayonet | Photography | |
| Bronica RF | | 6×4.5 | | | Bayonet | Photography | |
| Bronica SQA | 101.7 mm | 6×6 | 57 mm | | Bayonet | Photography | |
| Bronica GS1 | 85 mm | 6×7 | 80.5 mm | | Bayonet | Photography | |
| Mamiya 645 | 63.3 mm | 6×4.5 | 62 mm | | Bayonet | Photography | |
| Mamiya 6 | 56.2 mm (approx.) | 6×6 | | | Bayonet | Photography | |
| Mamiya 7/7II | 59 mm (approx.) | 6×7 | 49 mm | | Bayonet | Photography | |
| Mamiya RZ67 | 105 mm | 6×7 | 60 mm | | Bayonet | Photography | |
| Mamiya RB67 | 112 mm | 6×7 | 60 mm | | Bayonet | Photography | |
| Mamiya ZE | 45.5 mm | 35 mm | | | Bayonet | Photography | |
| Mamiya/Sekor E | 43.5 mm | 35 mm | 49 mm | | Bayonet | Photography | |
| Pentax 645 | 70.87 mm | 6×4.5 | 61.2 mm | | Bayonet | Photography | |
| Pentax 6x7 | 84.95 mm | 6×7 | 72 mm | | Bayonet | Photography | |
| Pentacon Six | 74.1 mm | 6×6 | 60 mm | | Breech lock | Photography | |
| Fujifilm G | 26.7 mm | 43.8x32.9 mm | 65 mm | | Bayonet | Photography (Digital) | Fujifilm GFX series |
| Rolleiflex SL66 | 102.8 mm | 6×6 | | | Bayonet | Photography | |
| Rolleiflex SL35 | 44.46 mm | 35 mm | 46 mm | | Bayonet | Photography | |
| RMS thread, society thread | 150/180 mm | | 0.8", Whitworth | 36 tpi | Screw | Microscope | older microscopes |
| Leica Nikon Biological | Unknown | | M25 | 0.75 mm | Screw | Microscope | |
| BD Mount | Unknown | | M26 | 0.7 mm | Screw | Microscope | Mitutoyo Olympus BD Nikon BD |
| Zeiss | Unknown | | M27 | 0.75 mm | Screw | Microscope | |
| TFL | 17.526 mm | 28 mm | M35 | 0.75 mm | Screw | Machine Vision | |
| TFL II | 17.526 mm | 35 mm | M48 | 0.75 mm | Screw | Machine Vision | |
| Pentax Auto 110 | 27 mm | 110 Film | 20.6 mm | | Bayonet | Photography | Auto 110 |
For small camera modules, used in e.g. CCTV systems and machine vision, a range of metric thread mounts exists. The smallest ones can be found also in e.g. cellphones and endoscopes. The most common by far is the M12x0.5, followed by M8x0.5 and M10x0.5.
* M4.2x0.2 (1/7" sensors)
* M4.6x0.25 (1/5", 2.4mm, 3.8mm sensors, industrial endoscopes)
* M5x0.35 (1/6", 1/5" sensors)
* M5.5x0.35 (1.7", 1/5.8", 1/5", 1/4" sensors)
* M6x0.35 (1/4", 5.2mm, 4.85mm sensors)
* M6.4x0.25 (1/3" sensors)
* M7x0.35 (1.8", 1.7", 1/6", 1/5", 1/4", 1/3.6", 1/3.2", 1/2.7", 4.85mm sensors)
* M8x0.35 (1/4", 1/3" sensors)
* M8x0.5 (1/5", 1/4", 1/3" sensors; sometimes occurs in diode laser modules)
* M9x0.5 (1/2.7", 1/3", 1/3.2" sensors; also commonly encountered in diode laser modules)
* M10x0.5 (1/4", 1/3" sensors)
* M12x0.5 (the S-mount, listed in the table)
* M22x0.5 (1/1.2" sensors)

## Focusing lens mount

The axial adjustment range for focusing Ultra wide angle lenses and some Wide-angle lenses in large format cameras is usually very small.
So some manufacturers (e.g. Linhof) offered special focusing lens mounts, so-called wide-angle focusing accessories for their cameras. With such a device, the lens could be focused precisely without moving the entire front standard.

## Secondary lens mount

Secondary lens refers to a multi-element lens mounted either in front of a camera's primary lens, or in between the camera body and the primary lens.
(D)SLR camera & interchangeable-lens manufacturers offer lens accessories like extension tubes and secondary lenses like teleconverters, which mount in between the camera body and the primary lens, both using and providing a primary lens mount. Various lensmakers also offer optical accessories that mount in front of the lens; these may include wide-angle, telephoto, fisheye, and close-up or macro adapters.
Canon PowerShot A and Canon PowerShot G cameras have a built-in or non-interchangeable primary (zoom) lens, and Canon has "conversion tube" accessories available for some Canon PowerShot camera models which provide either a 52mm or 58mm "accessory/filter" screw thread. Canon's close-up, wide- (WC-DC), and tele-conversion (TC-DC) lenses have 2, 3, and 4-element lenses respectively, so they are multi-element lenses and not diopter "filters".

## Lens mount adapters

Lens mount adapters are designed to attach a lens to a camera body with non-matching mounts. Generally, a lens can be easily adapted to a camera body with a smaller flange focal distance by simply adding space between the camera and the lens. When attempting to adapt a lens to a camera body with a larger flange focal distance, the adapter must include a secondary lens in order to compensate. This has the side effect of decreasing the amount of light that reaches the sensor, as well as adding a crop factor to the lens. Without the secondary lens, these adapters will function as an extension tube and will not be able to focus to infinity.