Want to purchase a lense for my Pentax K1000 slr 35 mm film camera. How do I know what lense will fit ?

Have purchased lensed on ebay that do not fit...they are listed as K mount lenses for Pentax cameras. What am I missing here?

The Pentax K1000 is an older no auto-anything camera as you well know. You are probably getting Kaf lenses. af standing for auto-focus (I think). I dont know if an auto-focus lens would work on a manual camera but I doubt it. I have found lenses for mine at flea markets and the like and dont know what exactly what the wording you are looking for is.

I will say this, my Pentax K1000 is a bit of a tough fit when it comes to some of my lenses. You have to get it all lined up just so and straight on or it wont even appear to go on. You should see a red dot on both the camera body and the lens. Line those two up and get the lens perfectly aligned with the body before you try to get it on there. My Canon cameras apparently have more clearance and arent as finnicky.

If the lenses you have are all manual they should work just fine. You shouldnt see any contacts at the mounting point. And there should be an adjusting ring towards the body end of the lens for aperture as well as the adjustment ring for focus (and zoom if you have a zoom lens). There should be a little bar sticking out of the camera side of the lens that actuates the aperture when the mirror flips up.

Hope this helps
:D

Look at the lenses. If they are K-AF mount, they are autofocus lenses and won't work on the older cameras. The newer lenses have electrical contacts.

If they are Pentax screw mount, you'll need an adapter to make them work.

And of course, there's the possibility that the lenses aren't even the K-mount at all because they're for a different brand of camera.

Photos of the lenses would help us out if you want to post them where we can see them.

Pentax is about the only company that never changed their lens mount once they created the K mount series. You can use their autofocus lenses on the old bodies and manual focus on the autofocus bodies. The older screwmount lenses can even be used via an adapter. If the lenses you bought don't fit, they are not K mount lenses.