Interchangeable lens

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A Leica R series teleconverter, with the female side of the Leica R bayonet mount. This side is also used on the camera body.

…and the male side.

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 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.

A lens mount may be a screw-threaded type, a bayonet-type, or a 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 (Nikon, Canon, Contax/Yashika, Pentax, etc.) are almost always incompatible. Many allege that this is due to the desire of manufacturers to "lock in" consumers to their brand. However, since there are other differences between manufacturers — specifically the flange focal distance from the lens mount to the film or sensor — one would not want to mount a lens which wasn't specifically designed for their type of camera, at least not without an adapter to correct the spacing.

In movie cameras, the two most popular mounts in current usage on professional 35 mm cameras are Arri's PL mount and Panavision's PV mount. 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.

1 List of lens mount types
2 List of lens mounts
- 2.1 Legend
3 Secondary lens mount
4 Notes
5 References
- 5.1 General references
6 See also
7 External links

List of lens mount types

These types are organized by category; find details in the section that follows.

Stills

Canon EF
Canon EF-S
Canon FD
Canon FL
Contax N
Contax/Yashica bayonet
Four Thirds System
Fujica X bayonet
Konica original bayonet
Konica AR 47mm bayonet
Leica M mount
Leica R bayonet
M42
Mamiya bayonet
Micro Four Thirds System
Minolta AF
Minolta MD
Miranda bayonet (all Miranda cameras had a dual bayonet/M42 screw mount)
Nikon F
Olympus OM
Pentax K
Sigma SA
T-mount (T-thread)
Yashica AF

Cine

Industrial

C mount
CS mount
Front-plate mount

List of lens mounts

This list of lens mounts is ordered by flange focal distance, from shortest to longest. It includes both digital, still photography and movie lens mounts.

OEM model line(s)	Interchangeable type name	Frame size	Camera type	Throat or thread diameter	Mount thread pitch	Mount type	Flange focal distance
	D mount	8 mm	movie and CCTV	0.625 inch	32 TPI	Screw	12.29 mm
	CS mount	16 mm	movie and CCTV	1 inch	32 TPI	Screw	12.52 mm
	C mount	16 mm	movie and CCTV	1 inch	32 TPI	Screw	17.526 mm (0.69 inches)
Canon EX			Camcorder			Bayonet	20 mm
	Micro Four Thirds		digital still	~38mm^A[›]		Bayonet	~20 mm
Bolex		16 mm	movie			Breech lock	23.22 mm
Leica M bayonet		35 mm	still	44 mm		Bayonet	27.8 mm
Canon screw mount		35 mm	still	M39	1 mm	Screw
Leica M39 screw mount		35 mm	still, enlargers	M39	26 TPI	Screw	28.8 mm
Narciss		16 mm	still	M24	1 mm	Screw	28.8 mm
Olympus Pen F		35 mm half-frame	still			Bayonet	28.95 mm
Hasselblad Xpan		35 mm panoramic	still			Bayonet	34.27 mm
Olympus E, Panasonic Lumix DMC-L, Leica Digilux	Four Thirds	17.3mm x 12.98mm	digital still	~44mm^A[›]		Bayonet	38.67 mm
Aaton universal		16 mm	movie			Breech lock	40 mm
Canon R		35 mm	still			Breech lock	42 mm
Canon FL		35 mm	still			Breech lock	42 mm
Canon FD		35 mm	still			Breech lock	42 mm
Fujica-X		35 mm	still			Bayonet	43.5 mm
Minolta MC/MD		35 mm	still			Bayonet	43.5 mm
Petriflex		35 mm	still			Breech lock	43.5 mm
Canon EF		35 mm	still	54mm^[1]		Bayonet	44 mm
Canon EF-S		APS-C	digital still	54mm^[2]		Bayonet	44 mm
Sigma SA		35 mm	still			Bayonet	44 mm
Paxette		35 mm	still	M39	1 mm	Screw	44 mm
Praktica B		35 mm	still			Bayonet	44.4 mm
Minolta AF		35 mm	still			Bayonet	44.5 mm
Rolleiflex SL35		35 mm	still			Bayonet	44.6 mm
Exakta, Topcon		35 mm	still			Bayonet	44.7 mm
Pentax K		35 mm	still			Bayonet	45.5 mm
Praktica	M42 lens mount	35 mm	still	42 mm	1 mm	Screw	45.5 mm
Yashica/Contax		35 mm	still			Bayonet	45.5 mm
Mamiya ZE		35 mm	still			Bayonet	45.5 mm
Olympus OM		35 mm	still			Bayonet	46 mm
Nikon F-mount		35 mm	still	44mm^[3]		Bayonet	46.5 mm
Leica R		35 mm	still			Bayonet	47 mm
Contax-N		35 mm	still			Bayonet	48 mm
Praktina		35 mm	still			Breech lock	50 mm
Arri standard		35 mm and 16 mm	movie			Tab lock	52 mm
Arri bayonet		35 mm and 16 mm	movie			Bayonet	52 mm
Arri PL		35 mm and 16 mm	movie			Breech lock	52 mm
Tamron	T2, T-mount or T-thread	35 mm	still	M42	0.75 mm	Screw	55 mm
Panavision PV mount		35 mm	movie			Breech lock	57.15 mm
Mitchell BNCR mount		35 mm	movie			Breech lock	61.468 mm
Mamiya 645		Medium format	still			Bayonet	63.3 mm
Leitz Visoflex II/III		35 mm	still			Bayonet (Leica M)	68.8 mm
Pentax 645		Medium format	still			Bayonet	70.87 mm
Arri Maxi PL		70 mm	movie	64mm			73.5 mm
Pentacon Six		Medium format	still			Breech lock	74.1 mm
Pentax 6x7		Medium format	still			Bayonet	84.95 mm
Leitz Visoflex I		35 mm	still	M39	26 TPI	Screw	91.3 mm
Mamiya RZ		Medium format	still			Bayonet	105 mm
Mamiya RB		Medium format	still			Bayonet	112 mm
Mamiya 7/7II		Medium format	still			Bayonet	~60 mm ???
Kowa Six/Super 66		Medium format	still			breech lock	79 mm
Hasselblad		Medium format	still			Bayonet	74.9 mm
Bronica S2A		Medium format	still	57	1	Bayonet	101.7 mm
Rolleiflex SL66		Medium format	still			Bayonet	102.8 mm

Legend

**Legend**
Column	Description
OEM model line(s)	primary manufacturer(s) or model line(s) with this mount
Interchangeable type name	interchangeable mounts used by multiple camera body and lens manufacturers
Frame size	maximum or typical film or image sensor format or size used for this mount
Camera type	digital, still, movie, CCTV, ...
Throat or thread diameter	Nominal inside-female or outside-male major diameter (D) with units: inch, mm, or M (ISO 68-1 metric thread pitch mm)
Mount thread pitch	(P) either: (Unified-thread) pitch count/inch, or (metric) mm/thread pitch
Mount type	Bayonet, Breech, Screw, ...
Flange focal distance	Nominal (mm) distance from film or image sensor to lens mount

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.

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 provides 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".

Notes

^ 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)) and suitable format for professional use in digital age. 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."^[4]
"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."^[5]
"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."^[6]

So:

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),^[7], 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).