I would go for the Sigma 10-20

I really like the composition of the third one. They all look like they could do with a bit of a tweak of levels and contrast.

Graet stuff! #2 for me, I love the composition and the rushing effect, and there's just enough of the trees showing that you can work out what it is.

Thanks Matt. What's confusing me is the lens looks like the aperture should be able to be controlled by the camera. The aperture control looks identical to my Pentax A 50mm. I am guessing the P setting on the lens is equivalent to the A setting on my other lenses. The mechanism looks identical. I will try it out in M though and sees if it is worth persevering with this lens.

Hmmm.....the lens I have does not appear to be either of the problem ones (no ball or thin wire pin). The lens fits fine and the lens mount looks identical to my other manual focus primes, with a rectangular pin. The only problem seems to be the lens stays wide open when mounted on my K7. The mount is R-P/K accorfing to the markings on the lens. Any ideas?

Yes that's it.

Thanks John, I guess that answers why its not working properly. Whoops. I will try and remove the pin.

I was a bit surprised it meters in Av using the aperture ring too, and after another fiddle with it it looks like the aperture actually remains wide open whatever I set on the aperture ring. The aperture ring works perfectly off-camera Any ideas?

I saw one of these lenses in a camera shop yesterday, and as it was in mint condition (and it's the same shop where I found my Sigma 24mm Super-wde II and Pentax 50mm f1.4 for £30 each) I took a punt and paid the £20 they were asking for it. I can't find much online about it, and was wondering if anyone knew what the P setting on the aperture ring is for? I thought it would be the same as the A setting on my other manual focus lenses, but it does not seem to be. The lens is strange in that 35mm is with the lens extended and 70mm is at the shorter end. I have not tried it out properly yet, but it seems to meter correctly in Av using the aperture ring to set the aperture. It also claims to be a macro lens, but only goes to 1:6 on the focusing ring, which is nice and chunky.
Does anyone here have one of these lenses, and if so, any info on it?

After a bit of research (based on info kindly supplied by Wobbly Goblin) I have decided I may sell the K7 and get an already converted camera. Not because I don't want to modify the K7, but because it's more convenient and cost effective.

Thanks for the pm I will get in touch with him! I have a few lenses with ir scale on them but af sounds like a good option. Look forward to seeing more of your ir work on the forum, and hopefully will have some of my own in the not too distant future!