Camera Mounts Sorted by Register

This is a list of known camera mounts (thanks to William-Jan Markerink, who provided most of the data in this table). I have sorted the mounts in order of decreasing register (flange distance) to help see what adaptations might be feasible with correct infinity focus. Generally speaking, a lens might be adapted to bodies farther down the list; moving upward means that a simple adapter (one with no optical elements) is impossible for an unmodified camera and lens while retaining infinity focus.

Where the distances are the same, or very close, things might or might not work. For example, adapting a Leica R mount lens (distance 47mm) to a Nikon F mount (distance 46.5mm) leaves only 0.5mm space, which might be too thin to make a usable adapter. Close cases also require that the thread or bayonet of the lens must be small enough to fit entirely inside the mount of the body, and this list gives no information. That said, there are examples where an adapter between two mounts of exactly the same distance is possible, notably the Pentax K, for which Pentax M42 adapters are readily available. Presumably Pentax designed the K mount with this in mind. Where no adapter is possible, it is sometimes possible to modify a camera body with a mounting flange from some other system; look here for an example. Note that this isn't a cheap option unless you are a Leica owner. Of course, we can also modify the lens.

Where the distances are widely different, e.g. when adapting most medium-format lenses to most 35mm bodies, an adapter is usually feasible. Some manufacturers even encourage this, e.g. Pentax and Contax.

More modern cameras make things much more complicated with proprietary electronic lens/body connections for aperture control, autofocus, etc; even after buying or making a mechanical adapter, many features of the lens just won't work. Most lens mount conversions sacrifice autofocus, automatic exposure, or both. In some cases, even the camera's light-metering and focus confirm are crippled. One exception is Canon and Sigma SA mounts; apparently the electronic protocols reportedly match, and the lens register seems to be identical. Someone in China has apparently converted a Canon L-series lens to work on his Sigma digital SLR; there is a discussion of the relevant issues in this forum.

A more challenging approach is to build circuitry to translate between camera and lens; this is done in a somewhat pricey conversion of Contax N lenses for modern cameras with automatic features supported.

I have tried to code each entry by color corresponding to the original image format:

35mm full-frame is yellow
Smaller formats are blue
Larger formats are green
Cinema and video formats are white

The same list is available in alphabetical order here.

Camera System Mount Type Register Diameter   Camera System Mount Type Register Diameter
Samsung NX-M bayonet 6.95     Topcon RE bayonet 44.7 38
Pentax Q bayonet 9.2     Voigtländer Bessamatic bayonet 44.7  
D-mount 0.625″×32tpi 12.29 15.88   ZM39 M39×26tpi 45.2 ±0.02 39
C-S mount 1″×32tpi thread 12.526 25.4   Asahiflex M37×1 thread 45.46 37
Bolex H8RX 1″×32tpi thread 15.31 25.4   K-mount bayonet 45.46 44
Nikon 1 bayonet 17 40   Mamiya/Sekor SX M42×1 thread 45.46 42
C-mount 1″×32tpi thread 17.526 25.4   M42 screw M42×1 thread 45.46 42
Fujifilm X bayonet 17.7 44   Pentax/Praktica M42×1 thread 45.46 42
Canon EF-M bayonet 18 47   Pentax K bayonet 45.46 44
Sony E bayonet 18 46.1   Petri bayonet 45.5 43
Micro Four Thirds bayonet 19.25 38   Ricoh breech mount 45.5  
L-Mount bayonet 20 51.6   Contax S M42×1 thread 45.5 42
Canon EX1/2 VL camcorder bayonet 20     Contax/Yashica bayonet 45.5 48
Bolex breech lock 23.22     Contarex bayonet 46  
Samsung NX bayonet 25.5 42   Olympus OM bayonet 46 46
Pentax Auto 110 bayonet 27     Nikon F bayonet 46.5 44
Leica M bayonet 27.8 44   Leica R bayonet 47 49
Konica Hexar RF bayonet 28.00 ±0.03     Contax N bayonet 48 55
Canon screw M39×24tpi 28.8 39   Icarex breech lock 48  
Narcissus M24×1 thread 28.8 24   Éclair CA-1 bayonet 48 46
Opema 38 thread 28.8     B4 bayonet 48 (air)  
Leica screw M39×26tpi 28.8 39   HDTV 2/3″ B4 bayonet 48  
Olympus Pen F bayonet 28.95     Zenit 4, 5, 6 bayonet 49.9 ±0.02  
Contax G1 bayonet 29 44   Praktina breech lock 50 46
Robot M26×0.5 thread 31 26   Adaptall bayonet(?) 50.7 54
Robot bayonet 31     Arri Maxi PL breech lock 52 64
Hasselblad Xpan bayonet 34.27 46   Arri PL breech lock 52 64
Nikon S bayonet 34.54 49   Arriflex bayonet 52  
Contax RF dual bayonet 34.85 44   Leica S bayonet 53  
Alpa bayonet 35     Edixa Rex bayonet 53  
1/2″ video bayonet 35.74     Werra breech lock 54 44.5
Alpa bayonet 37.8 42   Pentina breech lock 54.95  
Minolta V bayonet 38     T2 mount M42×0.75 55 42
Sony 1/2" Video bayonet 38     Topcon UV bayonet 55  
4/3 System digital bayonet 38.67 44   Panavision PV breech lock 57.15 49.5
Argus 38mm thread 39 38   Mamiya 7/7II bayonet 57.85 49
Aaton PL-40 breech lock 40 50   Mitchell BNCR breech lock 61.468 68
Konica Autoreflex bayonet 40.5 47   Hasselblad H System bayonet 61.63  
Konica F bayonet 40.5     Mamiya 645 bayonet 63.3 62
Miranda dual bayonet/screw 4-claw bayonet and 44×1mm screw mount 41.5     Contax 645 bayonet 64.00  
Argus 33mm thread 41.9 33   Leitz Visoflex II, III Leica M bayonet 68.8 44
Canon R/FL/FD breech or bayonet 42 48   Bronica ETRS bayonet 69.0 ±0.03  
Start breech lock 42     Pentax 645 bayonet 70.87 61.2
Zenit 7 bayonet 42 ??   Rolleiflex SLX bayonet 74  
Wrayflex M41.2×26tpi 42.05     Exakta 66 breech lock 74.1 60
Altix breech lock 42.5 34   Kiev 60/Kiev Six breech lock 74.1 60
Yashica Pentamatic, Pentamatic II bayonet 43 47   Pentacon 6 breech lock 74.1 60
Rectaflex bayonet 43.4     Hasselblad V System bayonet 74.9 69
Fujica X bayonet 43.5 49   Reflex Korelle 40.5 × 0.75 thread 77.5 40.5
Mamiya/Sekor CS bayonet ~43.5     Kilarscope M39×26tpi 78.8  
Mamiya/Sekor E bayonet ~43.5 49   Kowa Six/Super 66 breech lock 79  
Petriflex breech lock 43.5     Hasselblad 1000F/1600F multi start thread 82.1 78
Minolta SR/MC/MD bayonet 43.72 +0.01 -0.02 41   Kiev 88, Salut, Zenit 80 multi start thread 82.1 78
Canon EOS bayonet 44 54   Pentax 6×7 bayonet 84.95 72
Kiev 10,15 bayonet 44? 43.6   Bronica SQ bayonet 85 78
Paxette M39×1 thread 44     Leitz Visoflex I M39×26tpi 91.3 39
Praktiflex M40×1 thread 44 40   Kilarflex M39×26tpi 92.3  
Sigma SA inner bayonet 44     Zeiss Ikon Panflex bayonet 99.35  
Praktica bayonet 44.4     Novoflex bayonet 100  
Argus bayonet 44.45     Bronica S2A bayonet & 57×1 thread 101.7 57
Minolta AF bayonet 44.5 49.7   Rolleiflex SL66 bayonet 102.8  
Sony Alpha bayonet 44.5 49.7   Mamiya RZ bayonet 105 60
Rolleiflex SL35 (QBM) bayonet 44.6 46   Mamiya RB bayonet 112 60
Exakta bayonet 44.7 38   Zeiss Ikon Flektoskop, Flektometer screw 119.35  
Voigtländer Vitessa T bayonet 44.7     Bronica GS1 bayonet    
Kodak Retina Reflex bayonet 44.7     Zenit D external bayonet ??  

Stephen H. Westin stephen.westin36@gmail.com
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