With the modern day new mirrorless cameras like the Fuji X-T2 and the Sony A7-II, there's great fun in finding less-than-usual lenses in abandoned lens mounts, and adapt them to fit the camera of your choice.
There's a lot of adapters available for peanut prices if you want to try something exotic and this article lists a lot of options to get your lens and camera connected.
Don't forget to get a bunch of macro rings to add between camera and lens if that is your thing!
In this article I try to compile a comprehensive guide to adapting lenses to various types and brands of cameras and lens mounts. As you will have found out by now (or you wouldn't be reading this article), most camera manufacturers used their own, proprietary lens mounts to make sure that once a customer (that means you) bought into a system, they'd be hooked forever.
Over time some lens mounts proved to be outdated and they were abandoned and replaced with others. Some manufacturers even went out of business, leaving their lenses orphaned and their users grappling for a new system to buy in to.
Then, enter the time of DSLRs (Digital SLRs) and nowadays the EVIL (Electronic Viewfinder, Interchangeable Lens) mirrorless cameras, and a lot of companies jumped onto the bandwagon of adapting lenses with uncommon mounts to new cameras.
It's a mess out there with the above alone, but then there's also folks who like to cobble up their own 'adapters' and fit even less common lenses to their Fuji, Olympus, Panasonic or Sony EVIL cameras.
Read on and you will find some links to your liking, and even a whole table that lists lens register depths so you can calculate just how much space you need to overcome for that old lens to function on your new camera (or, more likely, how little space you have to cram an adapter into...)
In the near future, I will create a visual catalog of lens mounts, that will contain the most seen lens mounts so you can compare them against your unidentified thrift store find ;-).
Don't forget to bookmark this page, sooner or later you will need it... Press Cmd-D or Ctrl-D to bookmark!
Have a modern mirrorless camera and need to find an adapter to fit your lens? Try FotoDiox Pro.
Novoflex have an Adapter Finder on their page: https://www.novoflex.com/index.php
For specialist adapter making, visit http://www.zoerk.com
The epitome of adaptability are the Tamron Adaptall lenses, which had their own adapters for most big brands of the 1970s and 1980s era: http://www.adaptall-2.com shows you the lenses.
A very extensive article by Robert A. Monaghan on what adapters fit what cameras and how to get almost any lens on any other type body: http://web.archive.org/web/20021014232607/http://medfmt.8k.com/bronmounts.html
Get modern day lenses (mostly SLR lenses) on modern day bodies with stock made lens mounts from Leitax.com. For instance, fit your Leica-R lens to a Nikon body with a new rear mount on the lens, no adapter needed!
Want to get into building your own custom adapter? You need to know what distance lenses for different lens mounts register at, i.e. what the distance between lens mount and film or sensor should be. Below is a table that previously was published on a website by mr. J.W. Markerink (fellow Dutchman) but because it went offline I reproduce the table here as I cannot link to it.
Camera mounts & lens registers
CAMERA SYSTEM MOUNT TYPE REGISTER Aaton bayonet(?) 40.00 Alpa bayonet 37.80 Argus bayonet 44.45 Arriflex bayonet 52.00 Balda Baldamatic lll 44.70 Bolex breech 23.22 Bolex H8RX 1" x 32tpi thread 15.31 Braun Colorette 44.70 Braun Colorette Super 44.70 Braun Reflex Automatic 44.70 Bronica S2A bayonet & 57x1 thread 101.70 Bronica ETRS Bronica GS1 Compur 00 rear outer: 25x0.5 front inner: 22.5x0.5 rear inner: Compur 0 rear outer: 32.5x0.5 front inner: 29.5x0.5 rear inner: 29.5x0.5 Compur 1 rear outer: 39x0.75 front inner: 40x0.75 rear inner: 36x0.75 Compur 3 rear outer: 62x0.75 front inner: 58x0.75 rear inner: 58x0.75 Compur 5 rear outer: 92x0.75 front inner: 86x0.75 rear inner: 86x0.75 C-mount 1" x 32tpi thread 17.526 (0.69") C-S mount 1" x 32tpi thread 12.50 [also known as "1-32 UN 2A"] Canon EOS bayonet 44.00 Canon EX1/2 VL bayonet 20.00 Canon R/FL/FD breech or bayonet 42.00 Canon screw M39x1 thread 28.80 Contarex 46.00 Contax RF 34.85 Contax/Yashica bayonet 45.50 Contax G1 bayonet 29.00 D-mount 0.625" x 32tpi 12.29 Eclair bayonet 48.00 Exakta/Topcon bayonet 44.70 Exacta 66 breech lock 74.10 Edixa Electronica 44.70 Edixa-Rex bayonet 53.00 Hasselblad/Kiev88 multi start thread 82.10 Hasselblad 500/2000 bayonet 74.90 Icarex breech lock 48.00 (Icarex 35/35S/SL-706 45.50?) Iloca Electric 44.70 K-mount bayonet 45.46 Kilarflex 92.30 Kilarscope 78.80 Kiev 60/Kiev Six breech lock 74.10 Kiev 88 multi start thread 82.10 Kodak Reflex S 44.70 Kodak Reflex lll 44.70 Kodak Reflex IV 44.70 Kodak Reflex Instamatic Reflex 44.70 Kowa Six/Super 66 breech lock 79.00 Konica AR bayonet 40.70 Konica F bayonet 40.50 Konica RF Hexar screw 27.95 Leica M bayonet 27.95 (27.80?) Leica R bayonet 47.00 Leica screw M39x26tpi 28.80 Leitz Visoflex I M39x26tpi 62.50 (91.30 total) (both are sometimes mistaken for M39 x 1mm, a tiny difference, but enough to cause problems with some non-Leica M39 lenses) Leitz Visoflex II, III Leica M bayonet 40.00 (68.80 total) Mamiya ZE bayonet 45.50 Mamiya 645 bayonet 63.30 Mamiya RB bayonet 112.00 Mamiya RZ bayonet 105.00 Minolta AF bayonet 44.50 Minolta MD bayonet 43.50 Miranda dual BM/SM bayonet/M44x1 thread 41.50 Miranda TM only SM M42x1 thread 41.50 Miranda Laborec - bayonet/M44x1 thread 41.50 dual BM/SM Mirax Laborec BM/SM Laborec-bayonet/M46x1 thread 41.50 (Soligor TM only SM M42x1 thread 41.50 (Pallas TM only SM M42x1 thread 41.50 Narcissus M24x1 thread 28.80 Nikon bayonet 46.50 Novoflex 100.00 Olympus OM bayonet 46.00 Olympus Pen F bayonet 28.95 Olympus E1 bayonet 38.67 (38.80?) (adapter for OM lenses seems to require focusing beyond infinity, perhaps 0.13mm error due to film-thickness??) (aka 4/3 or four/thirds) Panasonic G1 Micro Four Thirds 19.20 (calculated from a T-mount -> G1 adapter with 35.80mm thickness (register T2 = 55mm; - 35.80 = 19.20) Paxette M39x1 thread 44.00 Pentacon 6 breech lock 74.10 Pentax 6x7 bayonet 84.95 (74.10?) Pentax 645 bayonet 70.87 Pentax/Practica M42x1 thread 45.46 (add film thickness, and get 45.50mm....;)) Practica bayonet Practiflex M40x1 thread 44.00 (not 45.50 as I wrote initially, see further down this page for more comments) Petriflex breech lock 43.50 Praktina breech lock 50.00 RAS Rectaflex 43.40 Retina lllS 44.70 Ricoh breach mount 45.50 RMS 0.800" x 36tpi thread Rolleiflex SL35 bayonet 44.60 Rolleiflex SL66 bayonet 102.80 Rollei 6008 75.32 Rollei 6008 shutter-adapter M39x0.75 31.68 Rollei 6008 bellows +67.00 (minimum extension; add both bellows and shutter-adapter and you get 174.00mm minimum) Samsung NX10 bayonet 25.50 Schneider M26x0.5 Sigma SA bayonet 44.00 S-mount Screw M12x0.5mm T2 mount M42x0.75 55.00 Topcon IC1 bayonet 55.00 Voigtlander Bessamatic 44.70 Voigtlander Ultramatic 44.70 Voigtlander Vitessa-T 44.70 Wrayflex M41.2 x 26tpi 42.05 Zeiss Ikon Flektoskop/F'meter 84.50 (119.35 total) Zeiss Ikon Panflex 64.50 (99.35 total) Zenith 3M M39x1 thread 45.46 Zenit 80 multi start thread 74.10
Abbreviations used here and in other literature
tpi = threads per inch
M = metric thread
Register = distance flange to film plane
BM = Bayonet Mount
TM = Thread Mount
RMS = Royal Microscopic Screw
Need diameters of a lens mount too? You might find the right information here: http://www.graphics.cornell.edu/~westin/misc/mounts-by-register.html