Flange focal distance

Last updated
Diagram illustrating the flange focal length of an SLR-type and a mirrorless-type camera Flange Focal Length (2 types camera).PNG
Diagram illustrating the flange focal length of an SLR–type and a mirrorless–type camera

For an interchangeable lens camera, the flange focal distance (FFD) (also known as the flange-to-film distance, flange focal depth, flange back distance (FBD), flange focal length (FFL), back focus [1] or register, depending on the usage and source) of a lens mount system is the distance from the mounting flange (the interlocking metal rings on the camera and the rear of the lens) to the film or image sensor plane. This value is different for different camera systems. The range of this distance, which will render an image clearly in focus within all focal lengths, is usually measured to a precision of hundredths of millimetres, and is not to be confused with depth of field.

Contents

Lenses can be adapted from one mount (and respective FFD) to another. FFD determines whether infinity focus can be accomplished with a simple non-optical adapter. Optics to correct for distance introduce more cost and can lower image quality, so non-optical lens adapters are preferred. A simple non-optical adapter holds the longer FFD lens the appropriate additional distance away from the sensor or film on the shorter FFD camera. A camera body with a shorter FFD can accept a larger number of lenses (those with a longer FFD) by using a simple adapter. A lens with a longer FFD can be more readily adapted to a larger number of camera bodies (those with a shorter FFD). If the difference is small, other factors such as the sizes and positions of the mounting flanges will influence whether a lens can be adapted without optics.

Standard mounts

Typically, camera bodies with shorter flange focal distance can be adapted more readily to lenses with longer flange focal distance.

MountFlange
focal distance
TypeFormatProductionPrime lensesZoom lensesWide/tele convertersMount convertersComments
Samsung NX mini 6.95 mmMirrorless1"2014–201521
Pentax Q-mount 9.2 mm [2] Mirrorless1/2.3" (6.17×4.55 mm) / 1/1.7"2011–20195301
M58×0.75 mm mount12 mmIndustrial24×36 mmIndustrial area and line scan cameras
D-mount 12.29 mmcine8 mm(8 mm movie cameras)
CS-mount 12.526 mm [3] [4] [5] TV1/4", 1/3", 1/2"(surveillance cameras)
Nikon Z-mount 16 mmMirrorless24×36 mm (FX)2018– 23 14 2 1 Lens count doesn't include 3rd party products.
APS-C (DX)2018– 1 5 Lens count doesn't include 3rd party products. Can use any of the 24x36 mm (FX) lenses and the FTZ/FTZ II mount adaptor.
DJI DL-mount 16.84 mm [6] MirrorlessSuper 352017–61For use on aerial drone and gimbal cameras.
Nikon 1-mount 17.00 mm [7] MirrorlessCX2011–2018381
C-mount 17.526 mm [8] [9] cine / TV8 mm, 16 mm, 1/3", 1/2", 2/3", 1", 4/3"~1926–(Bolex, Eclair and Bell & Howell)
Fujifilm X-mount 17.7 mmMirrorlessAPS-C2012– 23 14 2 1 [10]
Canon EF-M-mount 18.00 mmMirrorlessAPS-C2012– 3 5 0 1
Sony E-mount 18.00 mmMirrorlessAPS-C2010– 6 14 4 2

Lens count doesn't include 3rd party products. All FE lenses (see below) can also be used on APS-C E-mount cameras.

24×36 mm (FE)2013– 22 17 4 3

Lens count doesn't include 3rd party products.

Sony FZ-mount 19.00 mmcineSuper 352011–0203
24×36 mm2015–12
Micro Four Thirds System 19.25 mmMirrorless4/3"2008– 37 28 11
Hasselblad XCD mount 18.14 mm (+0.05/-0.00)MirrorlessMedium Format (127) 43.8×32.9 mm2017–1313for Hasselblad X System
Canon RF mount 20.00 mmMirrorless24×36 mm2018–12113
L-Mount [11] (Leica, Panasonic Lumix, Sigma, DJI)20.00 mmMirrorless24×36 mm, APS-C2014–1912The members of the L-mount alliance are Leica Camera, SIGMA, Panasonic, Ernst Leitz Wetzlar GmbH and DJI
LUMIX Panasonic [12] 20.00 mmMirrorless24×36 mm, APS-C2015–897L-mount system
JVC 1/3" bayonet mount 25.00 mmTV1/3" 3-CCD (5.24×2.94 mm)
Samsung NX-mount 25.50 mmMirrorlessAPS-C2010–201588
Fujifilm G-mount 26.7 mmMirrorlessMedium Format (127) 43.8×32.9 mm2017–721for Fujifilm GFX series cameras
Pentax Auto 110 27.00 mmSLR13×17 mm1978–19855100
RED ONE interchangeable mount 27.30 mmcine
Leica M-mount 27.8 (inner rails) <-> 27.95 (outer rails) mm [10] Mirrorless24×36 mm1954–aka Voigtländer VM-mount, Epson EM-mount, Zeiss ZM-mount as well as Konica KM-mount (Hexar RF) and Minolta M-mount (CL/CLE)
Nikonos 28.00 mm [13] underwater24x36 mm1963-20016000this is the underwater scale focusing camera
M39×26tpi mount 28.80 mmMirrorless24×36 mmLeica M39×26tpi aka LTM (Leica Thread Mount) aka L39 (not to be confused with M39×1)
M39×1/28.8 mount 28.80 mm [14] Mirrorless24×36 mm1948-1978Zorki M39×1/28.8 for Zorki cameras (not to be confused with M39×1 and M39x26tpi)
Contax G-mount 29.00 mmMirrorless24×36 mm1994–20056101
Olympus PEN F (film)28.95 mmSLR18×24 mm1963–1972162
Hasselblad XPan 34.27 mmMirrorless24×36 mm & 24×65 mm1998–20033000Identical to Fujifilm TX series cameras and mount
Contax RF-mount 34.85 mmMirrorless24×36 mm
Nikon S-mount 34.85 mmMirrorless24×36 mm1947–2005
1/2" TV bayonet mount 35.74 mmTV1/2" 3-CCDJVC, Hitachi, Panasonic, others, but not Sony
Minolta V-mount 36.00 mmSLRAPS-H1996–19993501 Vectis S-1, Vectis S-100, Dimâge RD 3000
Sony 1/2" TV bayonet mount 38.00 mmTV1/2" 3-CCD
Olympus Four Thirds System 38.67 mmSLR4/3"2003–201712302
Aaton mount40.00 mmcine16 mm/S16
Panavision SP70-mount 38.00 mmcine2018–35 mm & 65 mm
Konica F-mount 40.50 mmSLR24×36 mm1960–196517000
Konica AR-mount 40.50 mmSLR24×36 mm1965–1988361610
Canon FL-mount 42.00 mmSLR24×36 mm1964–1971
Canon FD-mount 42.00 mmSLR24×36 mm1971–199010734
Start (Soviet SLR)42.00 mmSLR1958–1964
Minolta SR-mount 43.50 mmSLR24×36 mm1958–20016
Fujica X-mount 43.50 mmSLR24×36 mm1980–1985
Pentaflex (16 mm cameras) 44.00 mmcine
Canon EF-mount 44.00 mmSLR24×36 mm / APS-H / APS-C1987–4764
Canon EF-S-mount 44.00 mmSLRAPS-C2003– 2 9 00
Praktica B-mount 44.40 mmSLR24×36 mm1978–1990
Sigma SA-mount 44.00 mmSLR24×36 mm / APS-C1992–141924
M39x144.00 mm [15] Mirrorless24×36 mm1950sBraun Paxette rangefinder cameras
Arri LPL44.00 mmcine25.54x36.70 mm2018-for Arri Alexa LF
Minolta/Konica Minolta/Sony A-mount 44.50 mmSLR24×36 mm1985– 42+0+17 50+2+13 6+0+2 2+0+0
APS-C2004–0+0+30+3+130+0+00+0+0
Rollei QBM 44.50 mm [16] SLR24×36 mm1970– Rollei, Voigtländer
Samsung Kenox mount 44.50 mmSLR24×36 mm1997–200212 (3?)00Although designed in 1990s, mount is manual-focus only; lenses mount and lock on a slightly modified Minolta A-mount adapters
Exakta 44.7 mm [17] SLR24×36 mm1936–1969
M39x145.20 mm [18] SLR24×36 mm1952–1968Early Russian SLRs (Zenit) (not to be confused with M39×26tpi and M39×1/28,8)
M37×1 45.46 mmSLR24×36 mm1952-1957Asahiflex I, Asahiflex IA (Tower 23), Asahiflex IIB (Tower 23/24), Asahiflex IIA (Tower 22)
M42×1 45.46 mmSLR24×36 mm1949–Pentacon, Pentax, Contax S, Praktica, Zeiss ZS, Zenit, many others (not to be confused with T-mount, which is M42×0.75)
Pentax K-mount 45.46 mmSLR / Mirrorless24×36 mm / APS-C1975–147 [19] 10883Used also by some Samsung, Ricoh, Chinon, Agfa, Vivitar, Petri and KMZ (Zenit) cameras. Lens count only for Pentax-branded lenses.
Contax C/Y-mount 45.50 mmSLR24×36 mm1974–20052453Used by some Contax and Yashica SLR cameras
Petri Bayonet 45.50 mmSLR24×36 mmPetri SLRs 1960-77.
Mamiya Z 45.50 mmSLR24×36 mm1980–
Kodak Retina DKL-mount 45.7 mmSLR / Mirrorless24×36 mm / 28×28 mm1958–1977 12+6 000DKL variants used by Retina Reflex S (034), Retina Reflex III (041), Retina Reflex IV (051, 051/N), Instamatic Reflex (062), Retina IIIS
Voigtländer Bessamatic DKL-mount 45.7 mmSLR24×36 mm1958–1967 11+2 1 00DKL variants used by Bessamatic, Bessamatic deLuxe, Bessamatic m, Bessamatic CS, Ultramatic, Ultramatic CS
Braun Paxette Reflex DKL-mount 45.7 mmSLR / Mirrorless24×36 mmDKL variant used by Paxette Reflex Automatic, Paxette Reflex Automatic II, Tower 33 Reflex, Tower 34 Reflex; Balda Baldamatic III; Witt Iloca Electric / Graflex Graphic 35 Electric; Wirgin Edixa Electronica / Revue Edixa Electronica
Voigtländer Vitessa T DKL-mount 45.7 mmMirrorless24×36 mm 4+?000DKL variant used by Voigtländer Vitessa T; Braun Colorette (Super) II, Colorette (Super) IIB, Colorette (Super) IIL, Colorette (Super) IIBL; Wittnauer Continental, Wittnauer Professional
Yashica MA-mount45.80 mmSLR24×36 mm1(measured); 230AF etc.
Olympus OM-mount 46.00 mmSLR24×36 mm1972–20023814
Nikon F-mount 46.50 mmSLR24×36 mm / APS-C1959– 213 117 Used by some Kiev F-mount cameras. Only Nikon manufactured lenses counted. Nikon claims that there is over 400 Nikkor lens models manufactured. [20]
Leica R-mount 47.00 mmSLR24×36 mm1964–2009
KMZ Zenit DKL-mount 47.58 mmSLR24×36 mm1964–1968 5 1 00Zenit/Зенит 4/5/6 "Байонет Ц", an unofficial DKL-mount variant
B4-mount 48.00 mmTV2/3" 3-CCD (9.6×5.4 mm)1992–Mount was in use since at least 1978, wasn't officially standardized until 1992.
Contax N 48.00 mmSLR24×36 mm2000–20054501
Tamron Adaptall/Adaptall-2 50.7 mmSLR24×36 mm1973-20061429326No camera uses Adaptall lenses natively, intended to be used with mount adapters. Many lenses have revisions, only original optical formulas are counted.
Arri Standard 52.00 mmcine
Arri B 52.00 mmcine
Arri PL 52.00 mmcine
Leica S-mount 53.00 mmSLR45×30 mm1996–
Mini T-mount 55.00 mmSLR24×36 mm1957–1962Taisei, M37×0.75
T-mount 55.00 mmSLR24×36 mm1962–Tamron T-400, M42×0.75 (not to be confused with M42×1)
YS mount 55.00 mmSLR24×36 mm–1969Sigma, Upsilon, Accura, Polaris, Sun, Aetna, Beroflex, Petri, Raynox, N.P.S., Formula, Dionar, Universal, Soligor, Yashica, Spiratone. M42×0.75 (not to be confused with M42×1) Same as T-mount but with aperture coupling
Mamiya 6 56.20 mmMirrorless6×6 cm1989–19953000Rangefinder camera system, flange focal distance might not be precise. [21]
Panavision PV-mount 57.15 mmcine1972–35 mm & 16 mm
Mamiya 7 59.00 mmMirrorless6×7 cm1995–20146000Rangefinder camera system
OCT-19 61.00 mmcine
Hasselblad H-mount 61.63 mmSLR6×4.5 cm2002–for Hasselblad H System
Mamiya 645 63.30 mmSLR6×4.5 cm1975–
Novoflex  [ de ] A-mount63.3 mmSLR(measured) "A"-type adapters for follow-focus system
Contax 645 64.00 mmSLR6×4.5 cm1999–
Zenza Bronica ETR 69.00 mmSLR6×4.5 cm1976–2004172
Pentax 645 70.87 mmSLR6×4.5 cm1984–25822
Rollei SLX 74.00 mmSLR6×6 cm1976–2005
Pentacon Six 74.1 mmSLR6×6 cm1956–1992Used also by Exakta 66 and Kiev 60 series cameras
Hasselblad V-mount 74.90 mmSLR6×6 cm1957–2013for Hasselblad V system
Kowa Six/Super 66 79.00 mmSLR6×6 cm1968–197490
Hasselblad 1000F & 1600F 82.10 mmSLR6×6 cm1948–1957
Salyut/Kiev mount 82.10 mmSLR6×6 cm1972–1980Used by Salyut-S/Салют-C, Zenit/Zenith-80, Kiev 88 cameras
Pentax 6×7 84.95 mm [22] or 85.00 mmSLR6×7 cm1969–19992523
Zenza Bronica SQ 85.00 mmSLR6×6 cm1980–200314
Zenza Bronica GS 85.00 mmSLR6×7 cm1983–2002902
Zenza Bronica S2A 101.70 mmSLR6×6 cm1959–1980
Rollei SL66 102.80 mmSLR6×6 cm1966–1992
Mamiya RZ 105.00 mmSLR6×7 cm1982–
Mamiya RB 112.00 mmSLR6×7 cm1970–
Ricoh 126C-Flex 62.22 mmSLR24×24 mm1968-1969
16-SP52 mm [23] Cine16 mm1965-1991Used on the Soviet Kinor 16 and Krasnogorsk cameras
Kiev-16U 31 mm [24] Cine16 mm3Used on the Soviet Kiev-16U camera
1KSR-1M57 mm [25] Cine35 mmUsed on the Soviet Konvas-1M, 7M, Automat cameras
1KSR-2M61 mm [25] Cine35 mmUsed on the Soviet Konvas-2M, 8M, Kinor-35 cameras
Vivitar TX 56.25 mmSLR24×36mm1976-1010Generic mount used to be attached on many cameras thanks to differents adapters

Precision

Flange focal distance is one of the most important variables in a system camera, as lens seating errors of as little as 0.01 mm will manifest themselves critically on the imaging plane and focus will not match the lens marks. Professional movie cameras are rigorously tested by rental houses regularly to ensure the distance is properly calibrated. Any discrepancies between eye focus and measured focus that manifest them­selves across a range of distances within a single lens may be collimation error with the lens, but if such discrepancies occur across several lenses, it is more likely to be the flange focal distance or the ground glass (or both) that are misset.

Film use

Due to research on optimal flange focal distance settings, it is currently considered better for flange focal distance to be set to somewhere within the film's emulsion layer, rather than on the surface of it. Therefore, the nominal flange focal depth will be equivalent to the distance to the ground glass, whereas the actual flange focal depth to the aperture plate will in fact be ~0.02 mm less.

See also

Related Research Articles

<span class="mw-page-title-main">Single-lens reflex camera</span> Camera that typically uses a mirror and prism system

A single-lens reflex camera (SLR) is a camera that typically uses a mirror and prism system that permits the photographer to view through the lens and see exactly what will be captured. With twin lens reflex and rangefinder cameras, the viewed image could be significantly different from the final image. When the shutter button is pressed on most SLRs, the mirror flips out of the light path, allowing light to pass through to the light receptor and the image to be captured.

<span class="mw-page-title-main">Rangefinder camera</span> Camera fitted with a rangefinder

A rangefinder camera is a camera fitted with a rangefinder, typically a split-image rangefinder: a range-finding focusing mechanism allowing the photographer to measure the subject distance and take photographs that are in sharp focus.

<span class="mw-page-title-main">Camera lens</span> Optical lens or assembly of lenses used with a camera to create images

A camera lens is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing an image chemically or electronically.

<span class="mw-page-title-main">Carl Zeiss AG</span> German optics company

Carl Zeiss AG, branded as ZEISS, is a German manufacturer of optical systems and optoelectronics, founded in Jena, Germany in 1846 by optician Carl Zeiss. Together with Ernst Abbe and Otto Schott he laid the foundation for today's multinational company. The current company emerged from a reunification of Carl Zeiss companies in East and West Germany with a consolidation phase in the 1990s. ZEISS is active in four business segments with approximately equal revenue in almost 50 countries, has 30 production sites and around 25 development sites worldwide.

<span class="mw-page-title-main">Digital single-lens reflex camera</span> Digital cameras combining the parts of a single-lens reflex camera and a digital camera back

A digital single-lens reflex camera is a digital camera that combines the optics and mechanisms of a single-lens reflex camera with a solid-state image sensor and digitally records the images from the sensor.

<span class="mw-page-title-main">Lens mount</span> Interface between a camera body and lens

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.

<span class="mw-page-title-main">M42 lens mount</span> Screw thread mounting standard for attaching lenses to 35 mm cameras

The M42 lens mount is a screw thread mounting standard for attaching lenses to 35 mm cameras, primarily single-lens reflex models. It is more accurately known as the M42 × 1 mm standard, which means that it is a metric screw thread of 42 mm diameter and 1 mm thread pitch.

<span class="mw-page-title-main">Pentax K-mount</span> Series of camera lens mounts made by Pentax

The Pentax K-mount, sometimes referred to as the "PK-mount", is a bayonet lens mount standard for mounting interchangeable photographic lenses to 35 mm single-lens reflex (SLR) cameras. It was created by Pentax in 1975, and has since been used by all Pentax 35 mm and digital SLRs and also the MILC Pentax K-01. A number of other manufacturers have also produced many K-mount lenses and K-mount cameras.

<span class="mw-page-title-main">Image stabilization</span> Techniques used to reduce blurring of images

Image stabilization (IS) is a family of techniques that reduce blurring associated with the motion of a camera or other imaging device during exposure.

<span class="mw-page-title-main">Tilt–shift photography</span> Camera technique

Tilt–shift photography is the use of camera movements that change the orientation or position of the lens with respect to the film or image sensor on cameras.

<span class="mw-page-title-main">C mount</span> Type of camera lens mount

A C mount is a type of lens mount commonly found on 16 mm movie cameras, closed-circuit television cameras, machine vision cameras and microscope phototubes.

The Sigma SA-mount is a lens mount by the Sigma Corporation of Japan for use on their autofocus single-lens reflex and mirrorless cameras. It was introduced with the SA-300 in 1992. Originally, the SA-mount was a dual-bayonet mount with inner (SA-IB) and outer (SA-OB) bayonets, the latter being a feature intended to mount heavy telephoto lenses, but never utilized by Sigma and consequently dropped with the release of the SD14 in 2007.

<span class="mw-page-title-main">Lens speed</span>

Lens speed is the maximum aperture diameter, or minimum f-number, of a photographic lens. A lens with a larger than average maximum aperture is called a "fast lens" because it can achieve the same exposure as an average lens with a faster shutter speed. Conversely, a smaller maximum aperture is "slow" because it delivers less light intensity and requires a slower (longer) shutter speed.

<span class="mw-page-title-main">Lenses for SLR and DSLR cameras</span>

This article details lensesfor single-lens reflex and digital single-lens reflex cameras. The emphasis is on modern lenses for 35 mm film SLRs and for "full-frame" DSLRs with sensor sizes less than or equal to 35 mm.

<span class="mw-page-title-main">Micro Four Thirds system</span> Digital camera design standard

The Micro Four Thirds system is a standard released by Olympus Imaging Corporation and Panasonic in 2008, for the design and development of mirrorless interchangeable lens digital cameras, camcorders and lenses. Camera bodies are available from Blackmagic, DJI, JVC, Kodak, Olympus, OM System, Panasonic, Sharp, Logitech Mevo and Xiaomi. MFT lenses are produced by Cosina Voigtländer, Kowa, Kodak, Mitakon, Olympus, Panasonic, Samyang, Sharp, Sigma, SLR Magic, Tamron, Tokina, TTArtisan, Veydra, Xiaomi, Laowa, Yongnuo, Zonlai, Lensbaby, Venus Optics and 7artisans amongst others.

<span class="mw-page-title-main">Sony E-mount</span> Lens mount designed by Sony for their camcorders and mirrorless cameras

The E-mount is a lens mount designed by Sony for their NEX and ILCE series of camcorders and mirrorless cameras. The E-mount supplements Sony's α mount, allowing the company to develop more compact imaging devices while maintaining compatibility with 35mm sensors. E-mount achieves this by:

<span class="mw-page-title-main">Panasonic Lumix DMC-GH2</span> Camera model

The Panasonic Lumix DMC-GH2 is a digital camera with HD video recording capability that is part of the Micro Four Thirds system. Though commonly referred to as a DSLR camera, it has no mirror or optical viewfinder, but has instead both a fold-out LCD screen and a electronic viewfinder.

The Pentax Q series is a series of mirrorless interchangeable-lens cameras made by Pentax and introduced in 2011 with the initial model Pentax Q. As of September 2012, it was the world's smallest, lightest interchangeable lens digital camera. The first models used a 1/2.3" back-illuminated sensor CMOS image sensor. The Q7, introduced in June 2013, uses a larger 1/1.7" type sensor. The Q system is now discontinued.

<span class="mw-page-title-main">Pentax Q</span> Camera model

The Pentax Q is a mirrorless interchangeable-lens camera introduced by Pentax on June 23, 2011.

<span class="mw-page-title-main">Lens adapter</span>

In photography and videography, a lens adapter is a device that enables the use of camera and lens combinations from otherwise incompatible systems. The most simple lens adapter designs, passive lens adapters provide a secure physical connection between the camera and the lens. Some passive adapters may include a mechanism for manual iris control. So called, active lens adapters will include electronic connections, enabling communication between the lens and the camera.

References

  1. "FOCUS BACK ON BACK FOCUS". 30 May 2009.
  2. Archived 2012-03-19 at the Wayback Machine pentax.jp
  3. Hornberg, Alexander (2007-02-27). Handbook of Machine Vision. John Wiley & Sons. ISBN   9783527610143.
  4. "CS-Mount | Edmund Optics". www.edmundoptics.com. Retrieved 2018-07-28.
  5. "Flangeback Distances | Universe Optics". Universe Optics. Retrieved 2018-07-28.
  6. "DJI launches Zenmuse X7 Super 35mm camera module with Raw video capture". dpreview.com.
  7. "Camera Mounts Sorted by Register".
  8. "main difference about C-mount vs. CS-mount" . Retrieved 2024-08-01.
  9. "C-Mount vs. CS-Mount" (PDF). ikegami.com. Retrieved 4 August 2023.
  10. 1 2 "Lens accessories | Accessories". FUJIFILM X Series & GFX – Global. 11 January 2024.
  11. "L-mount Alliance Overview".
  12. "LUMIX Panasonic L-mount". Panasonic.com.
  13. "Nikonos Lenses on Nikon dSLR?". Photo.net Photography Forums. 21 January 2012.
  14. "The Camera ZORKI Instruction Manual?" (PDF).
  15. Discussion of Zenit and Braun Paxette mounts
  16. Bertram Hönlinger, Carl Zeiss AG (2014): All Zeiss QBM lenses were designed for 44.5 mm. The 44.7 mm value found on some US sites is wrong.
  17. Wrotniak, J. Andrzej
  18. Zenit's mount history: M39x1/45,2
  19. "Zoom Lenses | PentaxForums.com". www.pentaxforums.com.
  20. Nikon F-Mount, nikonusa.com
  21. Ken Rockwell's Mamiya 6 page
  22. Camera Mounts Sorted by Register
  23. "16-SP (Krasnogorsk-2) adapters" . Retrieved 3 May 2024.
  24. "Industar-50 KIEV 16mm lens C mount ?". forum.mflenses.com. Retrieved 2024-05-03.
  25. 1 2 "Flange Focal Distances". Archived from the original on 2006-05-18. Retrieved 2024-05-03.