Lens mount

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Lenses sold per year by mount type
  Canon EF
  Nikon F
Female lens mount of an Minolta XD-7 with male mount of Minolta MC-Rokkor 58mm 1:1.4 lens
Pentax K-7 with visible lens mount

A lens mount is an interface — mechanical and often also electrical — between a photographic camera body and a lens. It is confined to cameras where the body allows interchangeable lenses, most usually the rangefinder camera, single lens reflex 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[edit]

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 only inserted in 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[who?] allege that these incompatibilities are due to the desire of manufacturers to "lock in" consumers to their brand.[citation needed]

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[edit]

Mount name Flange focal distance Frame size Throat or thread diameter Mount thread pitch Mount type Primary use Camera lines
S (a.k.a. M12) No Flange. Back focal distance from <1mm to 12mm. 1/6"  to 1"  12 mm 0.5 mm pitch Screw CCTV, PCB Edmund Optics μ-Video
Samsung NX mini 6.95 mm 1"  38 mm   Bayonet StillStill (Digital)
Pentax Q 9.2 mm 1/2.3", 1/1.7"      Bayonet StillStill (Digital)
D 12.29 mm 8 mm 15.88 mm (0.625 inch) 32 TPI Screw Cinematography  
CS 12.52 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  
Nikon 1 17 mm 13.2 x 8.8mm     Bayonet StillStill (Digital) Nikon 1 series
Fujifilm X 17.7 mm APS-C     Bayonet StillStill (Digital) Fujifilm X-series
Canon EF-M 18 mm APS-C 47 mm   Bayonet StillStill (Digital) Canon EOS M
Sony E 18 mm APS-C and 35 mm 46.1 mm (1.815 inch)   Bayonet StillStill (Digital) Sony Alpha NEX
Micro Four Thirds 19.25 mm 17.3 mm × 12.98 mm ~38 mmA[›]   Bayonet StillStill (Digital) Olympus Pen & OM-D series
Panasonic G, GF, GX & GH Series
Blackmagic Design Cinema Camera
Canon EX 20 mm       Bayonet Still
Bolex C 23.22 mm 16 mm     Breech lock Cinematography
1/3" bayonet mount 25 mm 1/3" (5.24x2.94) Bayonet Video JVC professional video cameras
Samsung NX 25.5 mm APS-C 42 mm   Bayonet StillStill (Digital)
Fujifilm G 26.7 mm 35 mm     Bayonet StillStill (Digital) Fujifilm GX-series
Pentax Auto 110 27 mm 110 film     Bayonet Still
Leica M 27.80 mm 35 mm 44 mm   Bayonet Still Leica M series
Leica CL
Minolta CLE
KM 28 mm (27.80 mm?) 35 mm 44 mm   Bayonet Still Konica Hexar RF
Canon screw mount   35 mm M39 1 mm Screw Still
M39 (a.k.a. L-Mount, LSM) 28.80 mm 35 mm M39 26 TPI Screw Still Leica M39 screw mount
Narciss 28.8 mm 16 mm M24 1 mm Screw Still
Olympus Pen-F 28.95 mm 35 mm half-frame     Bayonet Still
Contax bayonet 34.85 mm 35 mm   Double bayonet Still Contax I, II, III, IIa, IIIa
Kiev 35mm
Contax G 29.00 mm 35 mm     Breech lock Still
Canon SV 32.00 mm       Bayonet StillStill (Digital) Canon RC-701 & 760
Hasselblad Xpan 34.27 mm 35 mm panoramic     Bayonet Still
Nikon S 34.85 mm 35 mm     Bayonet Still Nikon Rangefinder
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     Bayonet Still
V 36.00 mm APS-H     Bayonet Still Minolta Vectis
Sony 1/2" bayonet mount 38 mm 1/2" (6.97x3.92) Bayonet Video Sony professional video cameras
Four Thirds 38.67 mm 17.3 mm × 12.98 mm ~44 mmA[›]   Bayonet StillStill (Digital) Olympus E
Panasonic Lumix DMC-L
Leica Digilux
Aaton universal 40 mm 16 mm     Breech lock Cinematography
Konica F 40.50 mm 35 mm 40 mm   Bayonet Still Konica F
AR 40.50 mm (40.7 mm) 35 mm 47 mm   Bayonet Still Konica Autoreflex
Miranda bayonet/M44 41.5 mm 35 mm and APS-C     Bayonet Still Miranda Camera Company
Canon FL 42 mm 35 mm     Breech lock Still  
Canon FD 42.00 mm 35 mm     Breech lock Still
Fujica X 43.5 mm 35 mm 49 mm   Bayonet Still Fujica-X
SR 43.50 mm 35 mm 44.97 mm   Bayonet (54°) Still Minolta SR/MC/MD
Petriflex 43.5 mm 35 mm     Breech lock Still
Mamiya/Sekor E 43.5 mm 35 mm     Bayonet Still
Canon EF 44.00 mm 35 mm 54 mm[1]   Bayonet StillStill (Digital) Canon EOS
Canon EF-S 44.00 mm APS-C 54 mm   Bayonet StillStill (Digital) Canon EOS
Sigma SA 44.00 mm 35 mm     Bayonet Still Sigma SA
Paxette 44 mm 35 mm M39 1 mm Screw Still
Praktica B 44.40 mm 35 mm     Bayonet Still
Minolta A 44.50 mm 35 mm and APS-C 49.7 mm (1.939 inch)   Bayonet (54°) Still Minolta AF/Alpha/Dynax/Maxxum
Sony α
Rolleiflex SL35 44.46 mm 35 mm 46 mm   Bayonet Still
Exakta, Topcon 44.7 mm 35 mm     Bayonet Still
Zenit M39 45.2 mm 35 mm M39 1 mm Screw Still
Pentax K 45.46 mm 35 mm     Bayonet Still
M37 45.46 mm 35 mm 37 mm 1 mm Screw Still Asahiflex
M42 45.46 mm 35 mm 42 mm 1 mm Screw Still Praktica
Y/C-mount 45.5 mm 35 mm     Bayonet Still Yashica/Contax
Mamiya ZE 45.5 mm 35 mm     Bayonet Still
MA ~45.8 mm 35 mm     Bayonet Still Kyocera Yashica 230 AF etc.
Olympus OM 46 mm 35 mm 46 mm   Bayonet Still
Nikon F 46.5 mm 35 mm 44 mm   Bayonet Still
Leica R 47.00 mm 35 mm     Bayonet Still
B4-mount 48 mm 2/3" (9.6x5.4) Bayonet Video Professional and broadcast video cameras
Contax-N 48 mm 35 mm     Bayonet Still
Praktina 50 mm 35 mm     Breech lock Still
T-Thread (Very earliest type) 50.7 mm 35 mm M37 0.75mm Screw Still Tamron
Adapt-A-Matic 50.7 mm 35 mm     Bayonet Still Tamron
Adaptall 1 & 2 50.7 mm 35 mm     Bayonet Still Tamron
Arri standard 52 mm 35 mm and 16 mm     Tab lock Cinematography
Arri bayonet 52 mm 35 mm and 16 mm     Bayonet Cinematography
Arri PL 52 mm 35 mm and 16 mm     Breech lock Cinematography
T 55 mm 35 mm 42 mm 0.75 mm Screw Still Tamron
YS Auto T-Thread 55 mm 35 mm 42 mm 0.75 mm Screw Still Sigma Corporation
T-thread 55 mm 35 mm 47 mm 0.75 mm Screw Still Tokina
Panavision PV 57.15 mm 35 mm     Breech lock Cinematography
B3-mount 58 mm 2/3"     Reverse bayonet Video Ikegami
Mamiya 7/7II 60 mm (approx.) 6×7     Bayonet Still
Mitchell BNCR 61.468 mm 35 mm     Breech lock Cinematography  
Mamiya 645 63.3 mm 6×4.5     Bayonet Still
Zeiss Panflex 5522/23 for Contax rf 64.50 mm 35 mm   Double bayonet Still
Leitz Visoflex II/III 68.8 mm 35 mm     Bayonet (Leica M) Still
Mavica 70 mm       Bayonet StillStill (Digital)
Pentax 645 70.87 mm 6×4.5     Bayonet Still
Arri Maxi PL 73.5 mm 70 mm 64 mm     Cinematography
Pentacon Six 74.1 mm 6×6     Breech lock Still
Hasselblad 74.9 mm 6×6     Bayonet Still
Kowa Six/Super 66 79 mm 6×6     Breech lock Still
Pentax 6x7 84.95 mm 6×7     Bayonet Still
Leitz Visoflex I 91.3 mm 35 mm M39 26 TPI Screw Still
Bronica S2A 101.7 mm 6×6 57 mm 1 Bayonet Still
Rolleiflex SL66 102.8 mm 6×6     Bayonet Still
Mamiya RZ67 105 mm 6×7     Bayonet Still
Mamiya RB67 112 mm 6×7     Bayonet Still
RMS thread, society thread Unknown   0.8", Whitworth 36 tpi Screw Microscope older microscopes
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

Focusing lens mount[edit]

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[edit]

A teleconverter attached between a camera and its objective

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[edit]

This lens adapter is a passive adapter designed for mounting a Nikon F mount lens to a Micro Four Thirds camera.
Main article: Lens adapter

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.[2]


^ A: The authoritative normative source for 4/3 standards information is Four-Thirds.Org and not 3rd-party reviews.

4/3's published facts:

  • "Size of the 4/3-type Sensor: The standard diagonal length of the sensor is 21.63 millimetres (0.852 in). It is half that of 35-mm film format (36 millimetres (1.4 in) x 24 millimetres (0.94 in) = 43.27 millimetres (1.704 in)) The image circle of the interchangeable lens is specified based on this diagonal length. The focal length is about a half that of a 135 film camera lens assuming the same angle of view."[3]
  • "The foundation for the high picture quality of the Four Thirds system is the lens mount, which is about twice the diameter of the image circle."[4]
  • "Differences between Four Thirds System mount and Micro Four Thirds System mount: Mount diameter reduction; As a result of research aimed at facilitating the design of compact, lightweight lenses while maintaining the current strength, the outer diameter of the lens mount has been reduced by approx. 6 millimetres (0.24 in). ... the Micro Four Thirds System ... specifies the optimum flange back length required to reduce camera size and thickness, assuming the omission of the mirror box. The flange back length has been reduced to about 1/2 that of the Four Thirds System."[5]


  • 21.63mm * 2 = 43.26 millimetres (1.703 in) or ~44mm
  • 43.26mm - 6mm = 37.26 millimetres (1.467 in) or ~38mm
  • (21.63mm)^2 = ( ( 17.3mm ^ 2 ) + ( 12.98mm ^ 2 ) ); See: Pythagorean theorem (5^2 = 4^2 + 3^2)

NOTE: Some published reviews of 4/3 instead cite the (female) "outside diameter" of the lens or mount as ~50mm (and micro-4/3 as ~44mm),[6] and not the appropriate major diameter (D) ~44mm which is the camera body's female mount inside-diameter and the lens's male mount outside-diameter (micro-4/3 ~38mm).

See also[edit]


General references[edit]

External links[edit]