Flange focal distance


For an interchangeable lens camera, the flange focal distance , flange focal length of a lens mount system is the distance from the mounting flange 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 known as the depth of focus.
Lenses can be adapted from one mount 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 higher FFD lens the appropriate additional distance away from the sensor or film on the lower FFD camera. A camera body with a lower FFD can accept a larger number of lenses by using a simple adapter. A lens with a higher FFD can be more readily adapted to a larger number of camera bodies. 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 mini6.95 mmMirrorless1"2014-201521
Pentax Q-mount9.2 mmMirrorless1/2.3" / 1/1.7"2011–5301
D-mount12.29 mmcine8 mm
CS-mount12.526 mmTV1/4", 1/3", 1/2"
Nikon Z-mount16 mmMirrorless24×36 mm2018–531
Nikon Z-mount16 mmMirrorlessAPS-C 2019-2Can use any of the 24x36 mm lenses and the FTZ mount adaptor.
DJI DL-mount16.84MirrorlessSuper 352017–40
Nikon 1-mount17 mmMirrorlessCX2011–1
C-mount17.526 mmcine / TV8 mm, 16 mm, 1/3", 1/2", 2/3", 1", 4/3"~1926–
Fujifilm X-mount17.7 mmMirrorlessAPS-C2012–121121
Canon EF-M-mount18 mmMirrorlessAPS-C2012–3501
Sony E-mount18 mmMirrorlessAPS-C2010–61142
Sony E-mount18 mmMirrorless24×36 mm 2013–111342
Sony FZ-mount19 mmcineSuper 352011–0203
Sony FZ-mount19 mmcine24×36 mm2015–12
Micro Four Thirds System19.25 mmMirrorless4/3"2008–372811
Hasselblad XCD mount18.14 mm MirrorlessMedium Format 43.8×32.9 mm2017–81for Hasselblad#XCD-System
Canon RF mount20 mmMirrorless24×36 mm2018–223
Leica L-Mount 20 mmMirrorless24×36 mm, APS-C2014–33
JVC 1/3" bayonet mount25 mmTV1/3" 3-CCD
Samsung NX-mount25.50 mmMirrorlessAPS-C2010–201588
Fujifilm G mount26.7 mmMirrorlessMedium Format 43.8×32.9 mm2017–721for Fujifilm GFX
Pentax Auto 11027 mmSLR13×17 mm1978–19855100
RED ONE interchangeable mount27.30 mmcine
Leica M-mount27.80 mmMirrorless24×36 mm1954–aka Voigtländer VM-mount, Epson EM-mount, Zeiss ZM-mount as well as Konica KM-mount and Minolta M-mount
Nikonos28 mmunderwater24x36 mm1963-20016000this is the underwater scale focusing camera
M39×26tpi mount28.80 mmMirrorless24×36 mmLeica M39×26tpi aka L39
Contax G-mount29.00 mmMirrorless24×36 mm1994–20056101
Olympus PEN F 28.95 mmSLR18×24 mm1963–1972162
Contax RF-mount34.85 mmMirrorless24×36 mm
Nikon S-mount34.85 mmMirrorless24×36 mm1947–2005
1/2" TV bayonet mount35.74 mmTV1/2" 3-CCDJVC, Hitachi, Panasonic, others, but not Sony
Minolta V-mount36.00 mmSLRAPS-H1996–19993501Vectis S-1, Vectis S-100, Dimâge RD 3000
Sony 1/2" TV bayonet mount38 mmTV1/2" 3-CCD
Olympus Four Thirds System38.67 mmSLR4/3"2003–201712302
Aaton mount40 mmcine16mm/S16
Konica F-mount40.50 mmSLR24×36 mm1960–196517000
Konica AR-mount40.50 mmSLR24×36 mm1965–1988361610
Canon FL-mount42.00 mmSLR24×36 mm1964–1971
Canon FD-mount42.00 mmSLR24×36 mm1971–199010734
Start 42.00 mmSLR1958–1964
Minolta SR-mount43.50 mmSLR24×36 mm1958–20016
Fujica X-mount43.50 mmSLR24×36 mm
Pentaflex 44 mmcine
Canon EF-mount44.00 mmSLR24×36 mm / APS-H / APS-C1987–4764
Canon EF-S-mount44.00 mmSLRAPS-C2003–2900
Praktica B-mount44.40 mmSLR24×36 mm
Sigma SA-mount44.00 mmSLR24×36 mm / APS-C1992–0
Arri LPL44.00 mmcine25.54x36.70 mm2018-for Arri Alexa LF
Minolta/Konica Minolta/Sony A-mount44.50 mmSLR24×36 mm1985–42+0+1750+2+136+0+22+0+0
Minolta/Konica Minolta/Sony A-mount44.50 mmSLRAPS-C2004–0+0+30+3+130+0+00+0+0
QBM44.5 mmSLR24×36 mmRollei, Voigtländer
Exakta44.7 mmSLR24×36 mm1936–1969
M39x145.2 mmSLR24×36 mm1952–1968Early Russian SLRs
M42×145.46 mmSLR24×36 mm1949–Pentacon, Pentax, Contax S, Praktica, Zeiss ZS, Zenit
Pentax K-mount45.46 mmSLR / Mirrorless24×36 mm1975–14110583lens count only for Pentax-branded lenses
Contax C/Y-mount45.50 mmSLR24×36 mm1974–20052453
Petri Bayonet45.50 mmSLR24×36 mm
Mamiya Z45.50 mmSLR24×36 mm1980–
Kodak Retina DKL-mount45.7 mmSLR / Mirrorless24×36 mm / 28×28 mm1958–197712+6000DKL variants used by Retina Reflex S, Retina Reflex III, Retina Reflex IV, Instamatic Reflex, Retina IIIS
Voigtländer Bessamatic DKL-mount45.7 mmSLR24×36 mm1958–196711+2100DKL variants used by Bessamatic, Bessamatic deLuxe, Bessamatic m, Bessamatic CS, Ultramatic, Ultramatic CS
Braun Paxette Reflex DKL-mount45.7 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-mount45.7 mmMirrorless24×36 mm4+?000DKL variant used by Voigtländer Vitessa T; Braun Colorette II, Colorette IIB, Colorette IIL, Colorette IIBL; Wittnauer Continental, Wittnauer Professional
Yashica MA-mount45.8 mmSLR24×36 mm1; 230AF etc.
Olympus OM-mount46.00 mmSLR24×36 mm1972–20023814
Nikon F-mount46.50 mmSLR24×36 mm / APS-C1959–213117Only Nikon manufactured lenses counted. Nikon claims that there is over 400 Nikkor lens models manufactured.
Leica R-mount47.00 mmSLR24×36 mm1964–2009
KMZ Zenit DKL-mount47.58 mmSLR24×36 mm1964–19685100Zenit/Зенит 4/5/6 "Байонет Ц", an unofficial DKL-mount variant
B4-mount48.00 mmTV2/3" 3-CCD
Contax N-mount48.00 mmSLR24×36 mm2000–20054501
Arri STD52.00 mmcine
Arri B52.00 mmcine
Arri PL52.00 mmcine
Leica S-mount53.00 mmSLR45×30 mm
Mini T-mount55.00 mmSLR24×36 mm1957–1962Taisei, M37×0.75
T-mount55.00 mmSLR24×36 mm1962–Tamron T-400, M42×0.75
YS mount55.00 mmSLR24×36 mm–1969Sigma, Upsilon, Accura, Polaris, Sun, Aetna, Beroflex, Petri, Raynox, N.P.S., Formula, Dionar, Universal, Soligor, Yashica, Spiratone. M42×0.75 Same as T-mount but with aperture coupling
Panavision PV-mount57.15 mmcine1972–35 mm & 16mm
OCT-1961.00 mmcine
Mamiya 64563.30 mmSLR6×4.5 cm
A-mount63.3 mmSLR "A"-type adapters for follow-focus system
Contax 64564.00 mmSLR6×4.5 cm
Pentax 64570.87 mmSLR6×4.5 cm1984–
Rollei SLX74.00 mmSLR6×6 cm–2005
Pentacon Six74.1 mmSLR6×6 cm1956–1992
Hasselblad 2000 & 50074.90 mmSLRHasselblad V mount
Hasselblad 1000F & 1600F82.10 mmSLR
Pentax 6×784.95 mm or 85.00 mmSLR6×7 cm1969–1999
Rollei SL66102.80 mmSLR6×6 cm
Mamiya RZ67105 mmSLR6×7 cm
Mamiya RB67111 mmSLR6×7 cm

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 groundglass that are misset.
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 groundglass, whereas the actual flange focal depth to the aperture plate will in fact be ~0.02 mm less.