Lens mount

File:Bajonett manual minolta.jpg

Male mount of Minolta MC-Rokkor 58mm 1:1.4 lens with female lens mount of an Minolta XD-7

File:Lens Units sold.svg

Lenses sold per year by mount type

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. ManyTemplate:Who allege that these incompatibilities are due to the desire of manufacturers to "lock in" consumers to their brand.Template: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 Template:As of 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	Template:Nts mm<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Template:Ntsh16 mm	Template:Nts mm		Breech lock	Cinematography	Kinor 16SP, Krasnogorsk-1, -2, -3<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref><ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref> 16mm movie cameras
Kinor 16SX	Template:Nts mm<ref name=":0">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Template:Ntsh16 mm	Template:Nts mm		Breech lock	Cinematography	Kinor 16SX-1M,-2M 16mm movie camera
OST/OCT-19	Template:Nts mm<ref name=":0" />	Template:Ntsh35 mm	Template:Nts mm		Breech lock	Cinematography	Konvas-2M, Kinor-35H 35mm movie cameras
Kiev-16U	Template:Nts mm<ref name=":1">Template:Cite book</ref>	Template:Ntsh16 mm	Template:Nts mm	Template:Nts mm	Screw	Cinematography	Kiev-16U/UE 16mm movie cameras
Kiev-16C	Template:Nts mm<ref name=":1" />	Template:Ntsh16 mm	Template:Nts mm	Template:Ntsmm	Screw		Kiev-1C 16mm movie camera
Canon SV	Template:Nts mm				Bayonet	Photography (Digital)	Canon RC-701 & 760
Argus C3	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm	20 TPI	Screw	Photography	Argus C3
Canon EX	Template:Nts mm	1/2"			Bayonet	Photography
Canon FL	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Breech lock	Photography
Canon FD	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Breech lock	Photography	Canon F series, A series, and T series SLRs
Canon FDn (a.k.a. "New FD")	Template:Nts mm	35 mm	Template:Nts mm		Bayonet	Photography	completely interchangeable with earlier FD lenses
Canon EF	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>		Bayonet	Photography	Canon EOS 35mm film SLR, Full Frame & APS-H DSLR
Canon EF-S	Template:Nts mm	Template:NtshAPS-C	Template:Nts mm		Bayonet	Photography (Digital)	Canon EOS APS-C DSLR
Canon EF-M	Template:Nts mm	Template:NtshAPS-C	Template:Nts mm		Bayonet	Photography (Digital)	Canon EOS M series Mirrorless APS-C Cameras
Canon RF	Template:Nts mm	Template:Ntsh35 mm and APS-C	Template:Nts 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	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>		Bayonet	Photography	Nikon Rangefinder
Nikon F	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>		Bayonet	Photography	Nikon F 35mm film SLR, Full Frame & APS-C DSLR
Nikon 1	Template:Nts mm	13.2 x 8.8mm	Template:Nts mm		Bayonet	Photography (Digital)	Nikon 1 series
Nikon Z	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography (Digital)	Nikon Z - Mirrorless Full Frame & APS-C
Sony Mavica	Template:Nts mm				Bayonet	Photography (Digital)
Sony E | FE	Template:Nts mm	Template:Ntsh35 mm and APS-C	Template:Nts mm (1.815 inch)		Bayonet	Photography (Digital)	Sony E/FE Mount Alpha Mirrorless Full Frame / APS-C| Sony NEX Mirrorless APS-C
Minolta SR	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet (54°)	Photography	Minolta SR/MC/MD
Minolta V	Template:Nts mm	Template:NtshAPS-H	Template:Nts mm		Bayonet	Photography	Minolta Vectis
Minolta A	Template:Nts mm	Template:Ntsh35 mm and APS-C	Template:Nts mm (1.939 inch)		Bayonet (54°)	Photography	Minolta DSLR AF/Alpha/Dynax/Maxxum Sony DSLR Alpha (α) A Mount
Pentax Auto 110	Template:Nts mm	Template:Ntsh110 film	Template:Nts mm		Bayonet	Photography	Pentax Auto 110 and Auto 110 Super
Pentax Q	Template:Nts mm	1/2.3", 1/1.7"	Template:Nts mm		Bayonet	Photography (Digital)
Pentax K	Template:Nts mm	Template:Ntsh35 mm and APS-C	Template:Nts mm		Bayonet	Photography	Used also by Ricoh, Chinon, Agfa, Vivitar and KMZ Zenit cameras
Leitz Visoflex I	Template:Nts mm	Template:Ntsh35 mm	Template:NtshM39	26 TPI	Screw	Photography
Leitz Visoflex II/III	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet (Leica M)	Photography
Leica M	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography	Leica M series Leica CL Minolta CLE
Leica R	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography
Leica L	Template:Nts mm	Template:Ntsh35 mm and APS-C	Template:Nts mm		Bayonet	Photography (Digital)	L-Mount Alliance (Leica, Panasonic, Sigma, DJI and Blackmagic Design cameras)
Contax RF	Template:Nts mm	Template:Ntsh35 mm	44 mmTemplate:Ntsh		Double bayonet	Photography	Contax I, II, III, IIa, IIIa Kiev rangefinders
Contax G	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Breech lock	Photography
Contax N	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography
Contax/Yashica	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography	Yashica/Contax
Yashica MA	Template:Ntsh~45.8 mm	Template:Ntsh35 mm			Bayonet	Photography	Kyocera Yashica 230 AF etc.
Fujica X	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography	Fujica-X
Fujifilm X	Template:Nts mm	Template:NtshAPS-C	Template:Nts mm		Bayonet	Photography (Digital)	Fujifilm X series mirrorless
Olympus Pen F	Template:Nts mm	Template:Ntsh35 mm half-frame			Bayonet	Photography
Olympus OM	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography
Four Thirds	Template:Nts mm	Template:Ntsh17.3 mm × 12.98 mm	Template:Ntsh~44 mmTemplate:Cref		Bayonet	Photography (Digital)	Olympus E Panasonic Lumix DMC-L Leica Digilux
Micro Four Thirds	Template:Nts mm	Template:Ntsh17.3 mm × 12.98 mm	Template:Ntsh~38 mmTemplate:Cref		Bayonet	Photography (Digital)	Olympus Pen & OM-D series Panasonic G, GF, GX & GH Series Blackmagic Design Cinema Camera
KM	Template:Nts mm (27.80 mm?)	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography	Konica Hexar RF
Konica F	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography	Konica F
Konica AR	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography	Konica Autoreflex
Samsung NX mini	Template:Nts mm	1"	Template:Nts mm		Bayonet	photography (Digital)
Samsung NX	Template:Nts mm	Template:NtshAPS-C	Template:Nts mm		Bayonet	Photography (Digital)
Samsung Kenox	Template:Nts mm	Template:Ntsh35 mm			Bayonet	Photography	Manual focus only; there is only one compatible camera - Samsung Kenox GX-1/Samsung SR4000.
DJI DL	Template:Nts mm<ref name="DJI DL mount lenses">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Template:Ntsh35 mm and APS-C	Template:Nts mm<ref name="DJI DL mount lenses"/>		Bayonet	Photography (Digital), Cinematography	For aerial drone and gimbal use; DJI Zenmuse X7, X9 and DJI Ronin 4D X9 cameras.
Icarex BM	Template:Nts mm	Template:Ntsh35 mm			Breech lock	Photography	Icarex 35S
D	Template:Nts mm	Template:Ntsh8 mm	Template:Nts mm (0.625 inch)	32 TPI	Screw	Cinematography
CS	Template:Nts6 mm<ref>Template:Cite book</ref>	Template:Ntsh1/3", 1/2"	Template:Nts mm (1 inch)	32 TPI	Screw	Cinematography / Industrial
C	Template:Nts mm (0.69 inches)	Template:Ntsh1/2", 16 mm, 2/3", 1"	Template:Nts 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.	Template:Ntsh1/6" to 1"	12 mm	0.5 mm pitch	Screw	CCTV, PCB	Edmund Optics μ-Video
Bolex Bajonet	Template:Nts mm	Template:Ntsh16 mm			Breech lock	Cinematography	effective focal distance Template:Nts mm (0.69 inches) due to beam splitter behind mount flange (accepts C-mount lenses with adapter)
1/3" bayonet mount	Template:Nts mm	1/3" (Template:Ntsx2.94)			Bayonet	Video	JVC professional video cameras
M39 (a.k.a. L-Mount, LTM)	Template:Nts mm	Template:Ntsh35 mm	Template:NtshM39	26 TPI	Screw	Photography	Leica M39 screw mount
Narciss	Template:Nts mm	Template:Ntsh16 mm	Template:NtshM24	1 mm	Screw	Photography
1/2" bayonet mount	Template:Nts mm	1/2" (Template:Ntsx3.92)			Bayonet	Video	Non-Sony professional video cameras
Alpa	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography
Sony 1/2" Video	Template:Nts mm	1/2" (Template:Ntsx3.92)			Bayonet	Video	Sony professional video cameras
Aaton universal	Template:Nts mm	Template:Ntsh16 mm	Template:Nts mm		Breech lock	Cinematography
Miranda bayonet/M44	Template:Nts mm	Template:Ntsh35 mm and APS-C			Bayonet	Photography	Miranda Camera Company
Petriflex	Template:Nts mm	Template:Ntsh35 mm			Breech lock	Photography
Sigma SA	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography	Sigma SA
Paxette	Template:Nts mm	Template:Ntsh35 mm	Template:NtshM39	1 mm	Screw	Photography
Praktiflex	Template:Nts mm	Template:Ntsh35 mm	Template:NtshM40	1 mm	Screw	Photography
Praktica	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography
Exakta, Topcon RE	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography
Zenit M39	Template:Nts mm	Template:Ntsh35 mm	Template:NtshM39	1 mm	Screw	Photography
M37	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm	1 mm	Screw	Photography	Asahiflex
M42	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm	1 mm	Screw	Photography	citation	CitationClass=web }}</ref> Pentax, Zenit
B4-mount	Template:Nts mm	2/3" (Template:Ntsx5.4)			Bayonet	Video	Professional and broadcast video cameras
Praktina	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Breech lock	Photography
T-Thread (Very earliest type)	Template:Nts mm	Template:Ntsh35 mm	M37	0.75mm	Screw	Photography	Tamron
Adapt-A-Matic	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography	Tamron
Adaptall & Adaptall-2	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography	Tamron
Arri standard	Template:Nts mm	Template:Ntsh35 mm and 16 mm	Template:Nts mm		Tab lock	Cinematography
Arri bayonet	Template:Nts mm	Template:Ntsh35 mm and 16 mm	Template:Nts mm		Bayonet	Cinematography
Arri PL	Template:Nts mm	Template:Ntsh35 mm and 16 mm	Template:Nts mm		Breech lock	Cinematography
Arri LPL	Template:Nts mm	Arri LF	Template:Nts mm		Breech lock	Cinematography
Arri Maxi PL	Template:Nts mm	Template:Ntsh70 mm	Template:Nts mm			Cinematography
T	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm	0.75 mm	Screw	Photography	Tamron
YS Auto T-Thread	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm	0.75 mm	Screw	Photography	Sigma Corporation
T-thread	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm	0.75 mm	Screw	Photography	Tokina
H-Mount	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm	0.75 mm	Screw	Photography	Hanimex (rebranding of Tokina M47)
Panavision PV	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Breech lock	Cinematography
B3-mount	Template:Nts mm	2/3"			Reverse bayonet	Video	Ikegami
Mitchell BNCR	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Breech lock	Cinematography
Zeiss Panflex 5522/23 for Contax RF	Template:Nts mm	Template:Ntsh35 mm	Template:Ntsh		Double bayonet	Photography
Kowa Six/Super 66	Template:Nts mm	Template:Ntsh6×6			Breech lock	Photography
Hasselblad	Template:Nts mm	Template:Ntsh6×6	Template:Nts mm		Bayonet	Photography
Hasselblad Xpan	Template:Nts mm	Template:Ntsh35 mm panoramic	Template:Nts mm		Bayonet	Photography
Bronica ETR	Template:Nts mm	Template:Ntsh6×4.5			Bayonet	Photography
Bronica RF		Template:Ntsh6×4.5			Bayonet	Photography
Bronica SQA	Template:Nts mm	Template:Ntsh6×6	Template:Nts mm		Bayonet	Photography
Bronica GS1	Template:Nts mm	Template:Ntsh6×7	Template:Nts mm		Bayonet	Photography
Mamiya 645	Template:Nts mm	Template:Ntsh6×4.5	Template:Nts mm		Bayonet	Photography
Mamiya 6	Template:Nts mm (approx.)<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Template:Ntsh6×6			Bayonet	Photography
Mamiya 7/7II	Template:Nts mm (approx.)	Template:Ntsh6×7	Template:Nts mm<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>		Bayonet	Photography
Mamiya RZ67	Template:Nts mm	Template:Ntsh6×7	Template:Nts mm		Bayonet	Photography
Mamiya RB67	Template:Nts mm	Template:Ntsh6×7	Template:Nts mm		Bayonet	Photography
Mamiya ZE	Template:Nts mm	Template:Ntsh35 mm			Bayonet	Photography
Mamiya/Sekor E	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography
Pentax 645	Template:Nts mm	Template:Ntsh6×4.5	Template:Nts mm		Bayonet	Photography
Pentax 6x7	Template:Nts mm	Template:Ntsh6×7	Template:Nts mm		Bayonet	Photography
Pentacon Six	Template:Nts mm	Template:Ntsh6×6	Template:Nts mm		Breech lock	Photography
Fujifilm G	Template:Nts mm	Template:Ntsh43.8x32.9 mm	Template:Nts mm<ref>{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>		Bayonet	Photography (Digital)	Fujifilm GFX series
Rolleiflex SL66	Template:Nts mm	Template:Ntsh6×6			Bayonet	Photography
Rolleiflex SL35	Template:Nts mm	Template:Ntsh35 mm	Template:Nts mm		Bayonet	Photography
RMS thread, society thread	Template:Nts/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<ref name="Lens Mounts Template:Pipe Edmund Optics">{{#invoke:citation/CS1|citation	CitationClass=web }}</ref>	Template:Nts mm	28 mm	M35	0.75 mm	Screw	Machine Vision
TFL II<ref name="Lens Mounts Template:Pipe Edmund Optics"/>	Template:Nts mm	35 mm	M48	0.75 mm	Screw	Machine Vision
Pentax Auto 110	citation	CitationClass=web }}</ref>	Template:Ntsh110 Film	citation	CitationClass=web }}</ref>		Bayonet	Photography	Template:NtshAuto 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.<ref>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

• 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

File:Teleconverter with Camera and lens.swn.jpg

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

File:Lens Adapter.jpg

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

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.<ref name="similaar">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref>

See also

• ISO metric screw thread
• Lens board

Notes

4/3's published facts:

• "Size of the 4/3-type Sensor: The standard diagonal length of the sensor is Template:Convert. It is half that of 35-mm film format (Template:Convert x Template:Convert = Template:Convert) 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."<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• "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."<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

• "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. Template:Convert. ... 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."<ref>{{#invoke:citation/CS1|citation

|CitationClass=web }}</ref>

So:

• 21.63mm * 2 = Template:Convert or ~44mm
• 43.26mm – 6mm = Template:Convert or ~38mm
• <math>\mathrm{(21.63\ mm)^2 = 17.3\ mm ^ 2 + 12.98\ mm ^ 2}</math>; See: Pythagorean theorem (<math>5^2 = 4^2 + 3^2</math>)

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),<ref name=dpr>{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> 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).

References

Sources

• {{#invoke:citation/CS1|citation

|CitationClass=web }} Template:Refend

External links

• SLR Mount Identification Guide
• List of Camera, Mount Type and Register for Mechanical & Optical Instruments
• https://web.archive.org/web/20081221083400/http://medfmt.8k.com/, Camera mounts & registers from Robert Monahan Medium Format Photography Megasite
• http://www.markerink.org/WJM/HTML/mounts.htm, Camera mounts & registers from Willem-Jan Markerink
• Camera Mounts Sorted by Register
• Alphabetical List of Camera Mounts
• Nikon Lens Nomenclature – a study in frustration
• Adaptall-2.com
• DPReview Hands-on preview of Fujifilm X-Pro1
• DPreview Hands-on preview of Canon EOS M
• Standard: GOST 10332-72 (in Russian) – M42×1/45.5, M39×1/28.8
• Standard: GOST 10332-63 (in Russian) – M39×1/45.2 (aka «Z39»), M39×1/28.8, bayonet «C» (cameras: «Zenit-5», «Zenit-6», «Zenit-7»), bayonet «Zenit-7» (in Russian)