Besides being plentiful, m42 lenses have the advantage of being easily adaptable to many other mounts; conversely, there are very few lens mounts (besides T2 and Adaptall, which are a different story anyway) that can be adapted for use on m42 bodies without loss of infinity (I can only think of DKL; m39 needs adjustment to reach infinity). But what's the point, someone might ask, of using non-native lenses on m42 bodies, given there are so many native m42 lenses? The point is that, having tried almost every m42 'fast fifty' lens there is, I'm curious to see what else I can use. So I'm looking for conversion ideas. But why not use the non-m42 lenses on their native bodies? On the one hand, I don't want to start a new system, not yet at least. On the other, there are obsolete systems which never produced a (relatively) advanced camera -- adapting their lenses is more or less the only way to use them (or at least to use them easily). So I probably wouldn't want to convert a Nikon, Canon, Konica, Minolta, Pentax or, say, Contax lens, unless it can be done very easily. I probably don't want to mess with (German) Exakta lenses: they were all produced in the m42 mount as well. (But I am curious about Praktica bayonet and Miranda, both screw and bayonet, lenses.)
So far I've had three (relative) successes and one failure. Number 1 is the Argus-Sekor 58mm f1.7, which optically is somewhat unusual: since only one camera was produced in this mount, converting the lens is the only way to use it with any sort of automation. Number 2 is the Petri 55mm f1.4, which is different from the ubiquitous 'Tomiokas': I've only managed to make it focus as far as about 15 feet. Number 3 is the Topcor 58mm f1.8, which is often claimed to be one of the sharpest fifties of the period: again, it doesn't quite reach infinity, but should be usable except for lanscapes. My failure was the Planar 50mm f1.4 in the QBM mount: the diaphragm simply doesn't work without the mount plate, and making a suitable replacement would require tools and skills far beyond what I posses; I guess I'll have to find a functional QBM body. Speaking of tools, my equipment is more or less limited to sandpaper, a file and a Swiss knife, which I use to tweak the replacement mounts cannibalised from other m42 lenses (such as cheap zooms). Since after conversion the lenses have fully manual aperture control, the handiest way to use them is on a body that supports aperture-priority auto-exposure, and ironically my go-to options in this category are the Contax 139 and the Yashica FX-D.
If you have any ideas or, better, experiences of similar conversions, please share!
So far I've had three (relative) successes and one failure. Number 1 is the Argus-Sekor 58mm f1.7, which optically is somewhat unusual: since only one camera was produced in this mount, converting the lens is the only way to use it with any sort of automation. Number 2 is the Petri 55mm f1.4, which is different from the ubiquitous 'Tomiokas': I've only managed to make it focus as far as about 15 feet. Number 3 is the Topcor 58mm f1.8, which is often claimed to be one of the sharpest fifties of the period: again, it doesn't quite reach infinity, but should be usable except for lanscapes. My failure was the Planar 50mm f1.4 in the QBM mount: the diaphragm simply doesn't work without the mount plate, and making a suitable replacement would require tools and skills far beyond what I posses; I guess I'll have to find a functional QBM body. Speaking of tools, my equipment is more or less limited to sandpaper, a file and a Swiss knife, which I use to tweak the replacement mounts cannibalised from other m42 lenses (such as cheap zooms). Since after conversion the lenses have fully manual aperture control, the handiest way to use them is on a body that supports aperture-priority auto-exposure, and ironically my go-to options in this category are the Contax 139 and the Yashica FX-D.
If you have any ideas or, better, experiences of similar conversions, please share!