Film Pentax K to M42 adapter


Hall of Famer
The Cosina C1 is a pentax K fitting (ie old film type)

I want to mount M42 extension rings & lens to it

Looking up adapters I see all sorts of K numbers & I'm not sure what is relevant to the Cosina C1.

Also if anyone here is looking to offload an adapter I may be interested.

Any advice appreciated
You essentially need the M42-PK adapter, which comes in a couple of versions. I'd recommend the original Pentax adapter, if you can find it: it is manufactured very nicely and mounts/unmounts without trouble. I'm not saying the other makes don't work, but sometimes you hear funny stories...

The other thing you need to pay attention to: M42 lenses have an aperture mechanism that works by pressing in a little pin on the back side of the lens. This aperture pin is not depressed by the M42/PK adapter (nor would it be by extension rings, typically). Therefore, lenses that work *only* in auto aperture mode will not stop down on the Pentax K mount camera. You *can* shoot these lenses wide-open, and you *can* convert Auto lenses to manual operation, but the best possibility, imho, is to buy M42 lenses that allow manual aperture operation by a manual/auto switch: You focus the camera with open aperture, then press the auto/manual switch, which takes the lens to shooting aperture, then you click the shutter (and Kodak does the rest, as the story goes)...


Hall of Famer
To be Clear Luke I want to mount M42 screw lens etc to a K mount fitting

Thanks Kompaketc - The Cosina C1 ia all manual camera (no auto anything) - one of the main reasons is to use the M42 extension ring as part of a pinhole assembly so definitely not bothered with fiddly controls.
My only other screw mount is a manual M42 Optik Meyer 30mm however I already have a Tamron Adaptall 28mm with a K adapter so less likely to use the Meyer


Hall of Famer
Cost is of primary consideration here and the original adapters are way way more than the Cosina I bought - as far as pinhole (which will be likely the main use) I could simply cut card & fit direct to the K mount - I used this same technique before on my Fuji STX1
I'll give this a try I think rather than risk jamming up a fine camera.
So you're trying to do close-up pinhole photography? Interesting... Maybe the best solution in this case would simply be to get Pentax K extension rings (they are dirt cheap, afaik) and get a Pentax body cap, drill a little pinhole in it and tadaa, pinhole setup? :) The Meyer 30mm alone may not be worth going for M42 -- especially since the Adaptall 28mm (which I have myself) is a pretty darn good lens...

(Don't get me wrong though: I love the option of getting old M42 lenses for next-to-nothing, and experiment with their looks. Just not what you seem to have in mind though)

Oh, and btw, the name "Kompaktkameratyp" translates into English as "compact camera guy" -- I think you just have to love the German language for those unbelievably large words it builds... (then again, the English equivalent is even longer, innit?)


Hall of Famer
Thanks Herr Kompaktkameratyp -a very good idea about the Pentax rings
I've looked a bit more closely at the K mount - ideally I need a whole flange to seat the pinhole card nicely & the K flange is in segments which is not ideal


Hall of Famer
Received a Pentax K Body Cap today - converted it to Pinhole & took a few photos as a test run
results if working to follow
Yes, please post some pictures you take with that setup -- and maybe a pic or two of the camera/pinhole itself as well? Interested in how large a hole you drilled (and what the image "look" is like with that diameter).
... oh, one more thing: I have one of those Lensbaby thingies which can load a pinhole plate as well. What's more interesting: you can also load differently shaped pinholes, and even plates that have multiple pinholes and such. Used that with digital cameras for experiments, and while many results are, err, strictly "experimental", some were really, really nice. Maybe if you want to go all out with you pinhole idea, make the pinhole section itself removable, so you can experiment with that? Some prior experimentation with a digital camera might be necessary, though, if you don't want to burn too much film...


Hall of Famer
Thanks - I'll have to check out the Lensbaby stuff - ideally I would like a digital camera with interchangeable lenses in meantime its the Cosina
Here is a photo already posted on another thread & yes designed for alternative pinholes

That appears to be a very sound construction -- and you cannot argue with the results, either: Very nicely done, indeed!
Note, btw, it's not either the Cosina or Lensbaby -- you can get Lensbaby stuff with the Pentax bayonet, and go on using the Cosina -- and/or get a cheap old digital Pentax body, which go for very little (e.g. K200D, very nice camera, rugged and weather-sealed, yet only around 100-150$). Yes, they are lower resolution than todays monsters, but of course they are easily more than adequate for the kind optical resolution a Lensbaby will provide (and, some will argue, for any other lens, too). Such is the beauty of the Pentax bayonet, actually: You can swap between analog and digital camera pretty seemlessly (except the digital are all APS-C only, so far) and use lenses from the 70es onwards...

Latest threads

Top Bottom