What is Flange Focal Distance? Lengths for Lens Mounts
The Flange Focal Distance is the distance between a camera lens mount and the film plane or image sensor.
The short distance on mirrorless cameras is why it is easy to adapt film lenses to those mounts. Space taken up by the mirror is replaced with a lens adapter.
Flange distance is also referred to as:
- Flange focal depth
- Flange back distance
- Flange focal length
- Back focus
- Flange-to-film distance
- Register
Film Plane Indicator / Focal Plane Mark
Each manufacturer uses a different mark to show the film or sensor plane location. The most common symbol is a circle with a line through it.
For Canon 35mm film cameras, such as the Canon AE-1, the mark is to the left of the prism. The distance from that mark to the front of the lens mark represents the flange focal distance.
The digital camera doesn’t use film, so Nikon referrers to it as the focal plane mark.
Successfully Adapting Lenses
The flange distance is what will determine if a lens can be adapted to a camera body. The flange distance of the lens needs to be larger than the camera it will be used on.
Mounting a lens further away than it was designed is possible. There are M42 (45.46mm) to Nikon F-mount (46.50mm) adapters. The added space acts like a short extension tube. The lens will not be able to focus to infinity.
Avoid adapters that use a correcting lens element. The cheap optics will degrade the lens’s image quality.
Different camera systems have different standard flange focal distances. Mirrorless cameras can all use lenses designed for DSLRs and film SLR cameras.
Vintage Lenses
Lenses designed for manual focus 35mm film cameras are popular to adapt. They have physical aperture rings. The adapters are simple because no connections are needed between a lens and the camera body.
For instance, it is possible to mount M42 screw mount lenses on Pentax K mount bodies by using an adapter.
Smart Adapters
“Smart adapters” have electrical contacts for control over auto focus and aperture. Compatibility will vary between different systems.
An example is using a Canon EOS lens on a Micro Four Thirds camera body.
Adapters Without Infinity Focus
There are some lens adapters that do not include optics to correct for infinity focus. These are for mounts with a longer flange distance than the design for the adapted lens.
A good example is a Minolta MD-mount to Nikon F-mount.
These can be useful for macro photography for attaching a lens onto a bellows. In my instance I wanted to attach a Minolta bellows lens onto a Nikon PB-4 bellows.
Common Camera Lens Mount Flange Focal Distances
| Mount | Flange Focal Distance | Type | Format |
|---|---|---|---|
| Samsung NX mini | 6.95 mm | Mirrorless | 1" |
| Pentax Q-mount | 9.2 mm | Mirrorless | 1/2.3" |
| M58×0.75 mm mount | 12 mm | Industrial | 24×36 mm |
| D-mount | 12.29 mm | cine | 8 mm |
| CS-mount | 12.526 mm | TV | 1/4", 1/3", 1/2" |
| Nikon Z-mount | 16 mm | Mirrorless | 24×36 mm |
| DJI DL-mount | 16.84 mm | Mirrorless | Super 35 |
| Nikon 1-mount | 17.00 mm | Mirrorless | CX |
| C-mount | 17.526 mm | cine / TV | 8 mm, 16 mm, 1/3", 1/2", 2/3", 1", 4/3" |
| Fujifilm X-mount | 17.7 mm | Mirrorless | APS-C |
| Canon EF-M mount | 18.00 mm | Mirrorless | APS-C |
| Sony E-mount | 18.00 mm | Mirrorless | APS-C & Full Frame |
| 24×36 mm (FE) | - | - | - |
| Sony FZ-mount | 19.00 mm | cine | Super 35 |
| Micro Four Thirds System | 19.25 mm | Mirrorless | 4/3" |
| Hasselblad XCD mount | 18.14 mm | Mirrorless | Medium Format (127) 43.8×32.9 mm |
| Canon RF mount | 20.00 mm | Mirrorless | 24×36 mm |
| Leica L-Mount (formerly CL-mount) | 20.00 mm | Mirrorless | 24×36 mm, APS-C |
| JVC 1/3" bayonet mount | 25.00 mm | TV | 1/3" 3-CCD (5.24×2.94 mm) |
| Samsung NX-mount | 25.50 mm | Mirrorless | APS-C |
| Fujifilm G-mount | 26.7 mm | Mirrorless | Medium Format (127) 43.8×32.9 mm |
| Pentax Auto 110 | 27.00 mm | SLR | 13×17 mm |
| RED ONE interchangeable mount | 27.30 mm | cine | - |
| Leica M-mount | 27.80 mm | Mirrorless | 24×36 mm |
| Nikonos | 28.00 mm | underwater | 24x36 mm |
| M39 lens mount (M39x26tpi mount) | 28.80 mm | Mirrorless | 24×36 mm |
| M39 lens mount (M39×1/28.8 mount) | 28.80 mm | Mirrorless | 24×36 mm |
| Contax G-mount | 29.00 mm | Mirrorless | 24×36 mm |
| Olympus PEN F (film) | 28.95 mm | SLR | 18×24 mm |
| Hasselblad XPan | 34.27 mm | Mirrorless | 24×36 mm & 24×65mm |
| Contax RF-mount | 34.85 mm | Mirrorless | 24×36 mm |
| Nikon S-mount | 34.85 mm | Mirrorless | 24×36 mm |
| 1/2" TV bayonet mount | 35.74 mm | TV | 1/2" 3-CCD |
| Minolta V-mount | 36.00 mm | SLR | APS-H |
| Sony 1/2" TV bayonet mount | 38.00 mm | TV | 1/2" 3-CCD |
| Olympus Four Thirds System | 38.67 mm | SLR | 4/3" |
| Aaton mount | 40.00 mm | cine | 16mm/S16 |
| Panavision SP70 mount | 38.00 mm | cine | - |
| Konica F-mount | 40.50 mm | SLR | 24×36 mm |
| Konica AR-mount | 40.50 mm | SLR | 24×36 mm |
| Canon FL-mount | 42.00 mm | SLR | 24×36 mm |
| Canon FD-mount | 42.00 mm | SLR | 24×36 mm |
| Start (Soviet camera) | 42.00 mm | SLR | |
| Minolta SR-mount | 43.50 mm | SLR | 24×36 mm |
| Fujica X-mount | 43.50 mm | SLR | 24×36 mm |
| Pentaflex (16 mm cameras) | 44.00 mm | cine | |
| Canon EF-mount | 44.00 mm | SLR | 24×36 mm |
| Canon EF-S-mount | 44.00 mm | SLR | APS-C |
| Praktica B-mount | 44.40 mm | SLR | 24×36 mm |
| Sigma SA-mount | 44.00 mm | SLR | 24×36 mm |
| Arri LPL | 44.00 mm | cine | 25.54x36.70 mm |
| Minolta/Konica Minolta/Sony A-mount | 44.50 mm | SLR | 24×36 mm |
| Minolta/Konica Minolta/Sony A-mount (APS-C) | 44.50 mm | SLR | APS-C |
| Rollei QBM | 44.50 mm | SLR | 24×36 mm |
| Samsung Kenox mount | 44.50 mm | SLR | 24×36 mm |
| Exakta | 44.7 mm | SLR | 24×36 mm |
| M39x1 | 45.20 mm | SLR | 24×36 mm |
| M37×1 | 45.46 mm | SLR | 24×36 mm |
| M42×1 | 45.46 mm | SLR | 24×36 mm |
| Pentax K-mount | 45.46 mm | SLR | 24×36 mm |
| Contax/Yashica (C/Y)-mount | 45.50 mm | SLR | 24×36 mm |
| Petri Bayonet | 45.50 mm | SLR | 24×36 mm |
| Mamiya Z | 45.50 mm | SLR | 24×36 mm |
| Kodak Retina DKL-mount | 45.7 mm | SLR | 24×36 mm / 28×28 mm |
| Voigtländer Bessamatic DKL-mount | 45.7 mm | SLR | 24×36 mm |
| Braun Paxette Reflex DKL-mount | 45.7 mm | SLR / Mirrorless | 24×36 mm |
| Voigtländer Vitessa T DKL-mount | 45.7 mm | Mirrorless | 24×36 mm |
| Yashica MA-mount | 45.80 mm | SLR | 24×36 mm |
| Olympus OM-mount | 46.00 mm | SLR | 24×36 mm |
| Nikon F-mount | 46.50 mm | SLR | 24×36 mm / APS-C |
| Leica R-mount | 47.00 mm | SLR | 24×36 mm |
| KMZ Zenit DKL-mount | 47.58 mm | SLR | 24×36 mm |
| B4-mount | 48.00 mm | TV | 2/3" 3-CCD (9.6×5.4 mm) |
| Contax N-mount | 48.00 mm | SLR | 24×36 mm |
| Tamron Adaptall/Adaptall-2 | 50.7 mm | SLR | 24×36 mm |
| Arri STD | 52.00 mm | cine | |
| Arri B | 52.00 mm | cine | |
| Arri PL | 52.00 mm | cine | |
| Leica S-mount | 53.00 mm | SLR | 45×30 mm |
| Mini T-mount | 55.00 mm | SLR | 24×36 mm |
| T-mount | 55.00 mm | SLR | 24×36 mm |
| YS mount | 55.00 mm | SLR | 24×36 mm |
| Mamiya 6 | 56.20 mm | Mirrorless | 6×6 cm |
| Panavision PV-mount | 57.15 mm | cine | |
| Mamiya 7 | 59.00 mm | Mirrorless | 6×7 cm |
| OCT-19 | 61.00 mm | cine | |
| Hasselblad H-mount | 61.63 mm | SLR | 6×4.5 cm |
| Mamiya 645 | 63.30 mm | SLR | 6×4.5 cm |
| Novoflex A-mount | 63.3 mm | SLR | |
| Contax 645 | 64.00 mm | SLR | 6×4.5 cm |
| Zenza Bronica ETR | 69.00 mm | SLR | 6×4.5 cm |
| Pentax 645 | 70.87 mm | SLR | 6×4.5 cm |
| Rollei SLX | 74.00 mm | SLR | 6×6 cm |
| Pentacon Six | 74.1 mm | SLR | 6×6 cm |
| Hasselblad V-mount | 74.90 mm | SLR | 6×6 cm |
| Kowa Six/Super 66 | 79.00 mm | SLR | 6×6 cm |
| Hasselblad 1000F & 1600F | 82.10 mm | SLR | 6×6 cm |
| Salyut/Kiev mount | 82.10 mm | SLR | 6×6 cm |
| Pentax 6×7 | 84.95 mm or 85.00 mm | SLR | 6×7 cm |
| Zenza Bronica SQ | 85.00 mm | SLR | 6×6 cm |
| Zenza Bronica GS | 85.00 mm | SLR | 6×7 cm |
| Zenza Bronica S2A | 101.70 mm | SLR | 6×6 cm |
| Rollei SL66 | 102.80 mm | SLR | 6×6 cm |
| Mamiya RZ | 105.00 mm | SLR | 6×7 cm |
| Mamiya RB | 112.00 mm | SLR | 6×7 cm |