Post away, you're most welcome.

It's curious really, because there is no doubt that the 12-24mm produces supernly sharp images.

It depends on what the test parameters are. In this case, the open aperture performance might be weak (it might not be, but I'm just supposing) but when stopped down it might be razor sharp. The relevant factor is that ultra-wides are normally used stopped down, so testing for open aperture performance is not really relevant.

Likewise, an 85mm portrait lens could be designed to have weak performance wide open to give nice flattering portraits, but to sharpen up a couple of stops down for when high sharpness was needed. Or it could be ultra-sharp wide open if that's what was inended. So a bald test needs to relate to the intention of the lens manufacturer and the perceived final use.

In summary, I think you can safely assumme that all the current Pentax lenses will give superb results on Pentax DSLRs. It's what they are designed for.

The tests in magazines have some place, but IMHO are largely a game that sells magazines. Just look closely and see how often the conclusions do not tally with the data presented...

If there's anyone there, all you have to do is ask. It's a matter of courtesy and very few churches will refuse you.

You can and do with any polariser, circular or linear.

The circular or linear refers to the direction of polarisation utilised.

I don't think anyone could answer this without seeing the good and not so good versions of the image.

7 element converters are much better than 4 element ones, but you might still get pretty average results, especially from zoom lenses.

The reason tyou can't get any communication with the camera is that is isn't any unless the converter has electrical contacts, as in the KA mount.

Check out what george has pointed out and enable use of aperture ring and you will then be able to use the converter.

Cheap converters don't give exciting results though.

Buy with confidence, the Pentax is a superb camera.

Bell & Howell are a very old optical firm that made lenses for cine and still cameras, plus cine projectors and all sorts of other things. The sort of lens you have though is likely to be from their later period when they branded lenses imported from Japan and sold them at the lower cost end of the market.

Personally I would get my money back, unless the lens is in such fine shape that you want to try it out. But don't expect too much.