I live in a screwmount world since I started photography, using M42 mount lens for my faithful Praktica, but I realized that I am perfectly ignorant of other lens mounting systems. Besides the Leica M39, all 35mm systems seem to have bayonet mounts, so I occasionally consider the thought of buying a bayonet-M42 adapter for some good glass, but I have no idea how many different systems there is. The only one I know for sure is the Pentax K-mount, because it superseded the M42 in Pentax bodies.
So here's a trivia question for you all: considering just the basic needs of a) sticking the lens to a body, and b) closing the diaphragm at the moment of exposures, how many types of adapter am I likely to consider? In other words, How many common bayonet mounts is there out there, considering only reasonably available equipement, not odd stuff?
Canon a couple of different types in additon to the AF mount, Minolta couple of different types MC, MD and the AF, Nikon, Pentax, Olympus and I know alot of the adapters are not automatic, so you have to manually adjust the aperture and use stop down metering.
Let us take a step back and look at your requirements:
Originally Posted by mhv
You have a collection of M42 screw mount lenses, and desire to get a newer camera with bayonet mount, for some purpose. You also like the idea of being able to fit your existing lenses to that camera and make them function as well.
Assuming that, you need a camera which can take an adapter that mates the M42 lens to its bayonet body. Brands of manual-focus cameras I can think of, off the top of my head, which allow that would be Canon Contax-Yashica, Konica, Minolta, Pentax-K, Praktica-B, and Rollei. These adapters fill in the gap between the lens and the camera, and retain the full focussing range of the fitted lens.
With the exception of the Rollei (which was designed to work with one model, the original SL35 which had stopped-down metering), none of these adapters can retain automatic diaphragm actuation: the M42 mechanism is triggered by a plunger pin which works parallel to the optical axis, but all others work in an axial direction. So the lens has to be used without any diaphragm automation whatsoever. Some of the adapters have the mechanism to force the lens to work as manual diaphragm, but most do not, requiring the lens to be switched to manual diaphragm completely. Forgetting to do so gives severe overexposure because no matter what setting you have on the aperture scale, it will simply refuse to stop down. And of course, for lenses without an auto-manual switch, those lenses would not be very practical.
The QBM mount by Rollei works in a different way, where the diaphragm actuator also works in a direction parallel to the optical axis. In other words, the adapter contains a simple relay mechanism which can indeed stop down the M42 lens fitted. But the companion camera with which it was introduced, the Rolleiflex SL35, had stopped-down metering, so it does not affect the functionality at all. With later models such as SL35M, SL35ME, SL35E and SL2000F and derivatives, they contain an extra coupling for full-aperture metering, so you can certainly do the metering with it, but you have to remember to stop the lens down manually when you are doing it.
Praktica provided the neatest arrangement where the adapter not only forces the lens to function as manual, but also contains a little box of tricks which electrically couples to the TTL metering system and tells it to meter at working aperture, effectively cutting off the aperture indexing and simulation system. I do not know if it is a good idea to make a start with the B-series now as Praktica has terminated the production of 35mm SLR cameras some years ago, and lenses are getting quite tricky to acquire.
There are also adapters which allow M42 lenses to fit other cameras but to retain the focussing range the adapter needs to contain a weak negative element which works like a weak tele-converter. Cameras allowing such adapters to be used include Nikon and Olympus. I do not see much point in starting a Nikon or Olympus system because the adapter introduces another element to the optical configuration, thus taking the edge off the lens performance.
Alternatively, you can also get a better camera body with M42 mount; I think Voigtlander's Bessaflex would be a very sound candidate if you want to follow this route.
Originally Posted by Seele
No, actually my requirement was to use bayonet-mounts lenses on my Praktica body. I don't need much in a body (I don't care for AE, AF, TTL metering). My Praktica L body has: a shutter, a crank, speed/f-stop dials, and a button. That's it, that's all. I'd like eventually to spend a few bucks on a nice lens, but don't want to feel limited to looking only for M42. Of course the Takumars and the Zeiss lenses are so far excellent for me, but a Nikon lens wouldn't be bad either.
Originally Posted by mhv
The main problem with the M42 lens mount was that it came out rather earlier than most; although it had a wider throat and shorter register than the then de-facto standard 35mm SLR, the Exakta, later cameras tend to have larger throat diameters or shorter register, or more than often, both, so that they could offer adapters to fill in the space in order to take advantage of the big pool of M42 lenses out there.
It also means that the reverse situation, fitting bayonet mount lenses to a M42 camera would be extremely difficult, if at all possible. Sure you might be able to get an adapter custom-made (more than likely at tremendous cost) but if the register is not matched, you are effectively using the lens on an extension tube making even general photography impossible.
If you like to use a Nikon (or any other brand) lens you cannot realistically do that without a Nikon camera. But then, there are still no shortage of very viable M42 lenses on the market. Those new ones by Voigtlander are superb, Russian ones are great value for money too. The "original" lenses supplied to dozens of M42 cameras over the years also makes a good resource, let alone the ones by third-party makers: apart from the more modern ones, do not forget houses such as Albert Schacht, Steinheil, Schneider, Rodenstock, Angenieux, Enna, Piesker, Tewe, Novoflex....
For myself, my requirements for M42 lenses are very well satisfied by "original" lenses supplied to Praktica over the years, mainly by Carl Zeiss and Hugo Meyer, along with a few exoticas by Angenieux, Steinheil, etc.
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Thanks for the informed replies, I think I will stick with the pool of available lenses (my 28mm SMC Takumar gave me the first pictures I'm proud of) for now, and will look into a new body when I feel it's really needed. I saw the new Cosina-Voigtlander M42 body, but didn't see if new lenses were manufactured for it, is it the case?
Unless you can make the adapter yourself the cost to have one made [assuming it's even possible] will exceed a budget body. In todays world you can sometimes buy bodies for less then the cost of a rear lens cap. You can't get custom machine work for that sort of money. Right now B&H is selling new Pentax K mount rear lens caps for $9. I've bought whole K mount cameras with a lens for little more then that.
I think you will find mating bayonet lenses onto your M42 a challenge. I know that Canon did a nice little adaptor ring that allowed using M42 lenses on their bodies. There was no automation and you had to use stop down metering. This mount was manufactured quite some time ago. I picked mine up in the early seventies. I have never heard of manufacturers making adaptors to allow their lenses to fit M42 bodies but I could easily be wrong in assuming that such adapters dont exist. Zoerk the renknowed adaptor manufacturer could manufacture something to order but it will cost a lot of money.
I think you are in a tough spot....
I knew of Leica -> M42 adapters, and that Tamron Adaptall has a Pentax ES adapter, but that is about it.
There maybe some odballs here and there taht we don;t know, kep looking ebay
Mama took my APX away.....
I believe Pentax makes a functional adapter, and that even their latest *ist (both film and d*g*t*l cameras) can use M42 lenses with these adapters.
-- Ole Tjugen, Luddite Elitist