They work well with K-to-M42 adapters, I had one a few years ago, ME Super exactly. The downside is that you must stop the lens down manually, but it's no surprise... I liked that option most of all other available bodies for M42, although I never had anything fancy like Memotron or Fuji 801.
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The biggest issue M series Pentax bodies have is winding problem, when film is wound but shutter isn't cocked. It is typically solved via CLA.
Ah, just maneuvering without film, there was a bit of oddity in the winding, but I thought it went away with a lens on (the STAR-D K-mount I had). I need to observe with close attention.
The mode control is neat, at first glance and peak at the manual!
I'd guess that a CLA for a ME Super would cost more than finding a clean properly working example. BTW, orphancameras.com has a wide range of manuals available for free for your downloading pleasure. Do send Mike Butkus the site master a few dollars. BTW, the MEs have a winder available, usually quite inexpensive. With the winder and a fast K mount 50mm - also available cheaply in the f2 version - you'd have a really nice shooter. See pentaxforums.com for much information on the wonderful world of Pentax.
This gets said a lot.
My question is...... how do you find that camera.?
And, unless the camera has a receipt, for a Recent CLA, from a Known/Good camera tech........ how do you define ... "a clean properly working example".?
If i Want/Need the camera.... i do not care if i spend 200 bux to CLA a body that can be bought fro 35 dollars.
It is way more important, to me, that i know i have a camera that is working the way it should.
Searching for an appropriate adapter can indeed be a pain in the rear. Some get stuck on the body, others, like mine, are thicker than it's necessary, so it didn't focus to infinity. I had to use a sandpaper to thin it down. Now it focuses to infinity and beyond But regardless, Pentax has the best support of "legacy" lenses.