No, film camera lenses are fine, the mount hasn't changed. A mystery that we'd need to look at in the flesh to make any further sense of it.

I wonder if some previous owner has been messing with it, but if it doesn't fit properly then ditch it rather than trying to force it. Repair would not be cost effective for such a low price lens.

Looking at it I can see no reason why it wouldn't fit. I presume other lenses that you have fit perfectly well?

If you set the lens to an aperture, let's say f/8 and operate that lever by the protruding guard does the lens stop down smoothly and without hesitation? I was just wondering if the lever was jammed.

Set it back to "A" after that and the lens should fit without any problems onto any Pentax body. There isn't some adapter already on your camera is there? If so, remove that before you fit this lens.

If it's a Pentax-A lens then it has to, unless there's something very wrong with it. Can you post an image of the back of the lens?

I don't think the camera stays switched on with time lapse. Doesn't it go into standby? That would also imply that a mains supply was handy, so out in the field that would be little use.

Mind you, if that was the purpose then it sounds like a professional requirement and the cost can then be covered by the fees charged.

AC adapters sell very few in the UK I would guess, so they aren't going to be cheap from any manufacturer. No point being surprised!

Having said that, the batteries last so long that I've never felt the need for an AC adapter. What sort of application is envisaged that makes it desirable?

Please don't post the same question in more than one place.

I'll close this one.

Yes you can use it. Set the aperture ring on A and you have a fully functional lens with your K-x. It will still be manual focus of course!

Nothing to do with us here Gwyn, a totally different thing and just part of ePHOTOzine.

If you go down to the bottom of the page and click Contact then all the contact details come up. It looks like it will need to be a phone call as I can't see an e-mail form either.