General information on the EXA mount.
The Exakta or EXA-mount has its origins in the Ihagee Kine Exakta of 1936 – a camera which in many ways paved the way for the modern concept of an SLR and is widely credited for having been the first 35 mm SLR. While the Kine Exakta was an instant hit, manufacture of the camera seized in 1940 because of the war. After the war Ihagee – the manufacturer of the Exakta – met a fate very much like that of Zeiss, meaning that there was an Ihagee both in East and West Germany, and both wanted to use the name.
Even though the war was a major spanner in the Ihagee works, and even though after the war the main manufacturer of Ihagee cameras (Ihagee East) was locked up behind the iron curtain, the Ihagee Exakta and Exa lines of cameras were a huge hit in the late 40’s and 50’s. Not only were they technlogically very advanced, but also partially aided by their iconic shape, and high media profile (e.g. featuring prominently in Hitchcock’s Rear Window). As a result of the popularity of the body, EXA lenses were manufactured in the thousands (not thousands of lenses, but thousands of different lens models). Time was, when the typical lens would always be available in two mounts: Exakta (first) and M42 (second).
Aside from the two Ihagee’s (East and West), the Exakta lens mount was also taken up my other camera manufacturers. Most prominent of these was Topcon (originally Tokyo Kogaku Kikai Kabushiki-Kaisha). Topcon’s first, and highly acclaimed line of SLR’s used the EXA bayonet for attaching lenses (leading to that the mount is sometimes referred to as the Exakta/Topcon mount. Also, the mount was briefly used by Mamiya for a line of SLR’s which were mostly sold as rebrands (among others as ‘Sears’) as well as a trio of relatively obscure camera manufacturers (Tokiwa Seiki, Corfield, and ELOP).
That’s ancient history. Why should I care?
No, you should not. Its entirely up to you. But there are several reasons for why caring about a prewar lens mount might be useful.
The attractiveness of the EXA mount for those who want to dabble with old lenses lies on two fronts: Firstly, as EXA-mount lenses go as far back as the pre-war era, and had their heyday before the advent of the Japanese SLR, EXA-mount lenses open a window into a time when Germany (pre-war as well as East and West) were the undisputed kings of cameras and optics. As a result of this, Exakta is one of the go-to -mounts (the other being M42) for lenses by as diverse a range of German manufacturers as Carl Zeiss Jena to Rodenstock; Meyer-Optik to Schneider Kreuznach as well as many less well known manufacturers such as Enna, ISCO, Kilfitt, Piesker, Schacht, Steinheil. Furthermore, after the Japanese adoption of the Exa mount, also several early Japanese manufacturers offered lenses for the EXA mount, among them household names such as Canon, Nikon, and Olympus, as well as some less well known brands. In spite of the limitations* defined by the size of the mount, the EXA-mount even for some time carried the fastest serial-produced lens of its time – the fabled Taika Harigon 58/1.2
The second attraction is economical: As EXA lenses have traditionally been less easily adapted, partially due to the convolution inherent in the way the mount evolved, many classic lenses that are available in both M42 and EXA mounts, can regularly be had more cheaply in EXA-versions. Often way more cheaply…
* Like many older mounts, the EXA-mount is relatively small. The inner diameter of the mount is merely 32,5 mm, and the outer diameter (prongs included is 37,5 mm). This makes the mount actually narrower that the M39 rangefinder mount and places a significant limitation on the size of a lens’ rearmost optic.
There are basically two versions of this story: Vanilla EXA and … well … EXtrA weird
And then there are two types of audiences: Mirrorless users and dSLR users. First, I’ll talk to the mirrorless audience:
Early EXA lenses (direct coupling aperture control or preset aperture control) are easy as pie. You buy any old EXA to <your mirrorless camera mount> dumb adapter (I use one I bought on aliexpress for <10€ ), mount your lens, and boom!
‘Auto’ Exa lenses (those with the funny-looking pod sticking out of the side of the lens) are no different, assuming the pod works as it should (It should allow you to lock the aperture in manual mode). Mount, and boom!
“Nonstandard” EXA-mount lenses … Well now. Especially Topcon was prolific at devising extensions to the EXA mount, and depending on the implementation of your EXA-to-whatever adapter, some of those extensions might spell trouble, and might in fact preclude your mounting the lens on the adapter. My basic recommendation: ask around.
External EXA-mount lenses? If you’re comfortable with making a DIY adapter…
How about those dSLR’s?
With the relatively short flange focal distance of the EXA mount (44,7 mm), you’re in luck your dSLR’s mount is Canon EF, in which case you can use a dumb adapter (with all the caveats mentioned above), but as all other dSLR either have prohibitive flange focal distances, you’ll either have to accept an adapter with optics (such are currently available al least for Nikon F, Pentax K and Sony A) or accept a crop factor (there used to be adapters for FourThirds, and you might still find one 2nd hand)
Identifying the EXA mount?
See more here.