Well the K mount has been in use since 1975 (12 years longer than Canon's EF.)

Currently about the same for mine too, but again it's only if they need fixing. I get them checked every year (free through work) but maintenance procedures are only if they need it...

Thanks, I may get tempted by that.
I do have a PKA adaptall-2, and should have a couple of PK ones too, though the first 3 adaptall lenses I checked were all without any mounts.
I know I can easily get the PK ones for £10, but the PKA ones are definitely preferable.

On Saturday I succumbed to LBA again, after spotting a Tamron SP 90mm f/2.5 at the local boot sale.
At first I managed to resist, but after walking off I remembered there was a macro Tamron that matched those details that actually had a rather good reputation, so went back for a second look. The body was a little grubby, but sure enough it was a macro, so I asked for the price, saying that I thought it might fit my camera. Lucky for me it was only £1 - and the optics were MUCH cleaner than the body!

After getting home I found I had to switch the Adaptall mount. If I can find which mount was originally fitted I'm fairly sure I can get more than my £1 back for that on e-bay. A quick test tonight has confirmed the lens works just fine, so with a bit of careful cleaning it should be fairly similar to the ones I've seen on e-bay go for £100+

I think I might end up selling my Cosina macro...

Peter
I don't think there are any AF M42 lenses in the world, but I gather the 55mm f1.8 is still regarded as a nice lens, as are the various K mount 50mm lenses. With the K5 autofocus is not available whilst shooting video so AF may not be an issue for you (Focus confirmation is still shown in the viewfinder)
For AF you're basically restricted to F, FA, & DA series lenses. These and the A series will give you camera control of the aperture, earlier lenses need green button mode for correct exposures. I'm not sure if this affects video exposures at all (I hardley ever shoot video).

Assuming your after AF for your portraits & landscapes I'd recomended the F50 /1.7 which can be had second hand within your budget. The wide aperture is ideal for portraits and with the crop factor the focal length is close to perfect too
For landscape a wider viewpoint is often desired so a DA35 /2.4 is another option that may suit you giving a field of view similar to the human eye.
If your not bothered by the lack of AF then A series lenses become a cheaper alternative.
I find the standard kit zoom performs reasonably as well...

As far as M42 adapters go the proper Pentax one is generally highly recomended, though I've not had any issues with the much cheaper chinese clones of it. Do be aware that some are sold with a mounting flange that prevents infinty focus, the good ones sit inside the K mount.

Provided the menu setting 'shoot without lens' has been changed to yes you should be able to shoot video with any lens that works for stills, though of course some will perform better than others.

I see David beat me to it - his linked adapter looks just the job.

I like the idea of a 25-350mm!

If I could afford the delivery charges I'm sure convertion would be a minor issue There's likely to be plenty of room for an adapter if you want anything closer than infinity - just think how much extension you'd need to focus down to mere 200m.

Thanks for the heads up Chris.

I already read f11 and had also grabbed craft & vision 1 in the past, but wasn't aware of C&V2.
I don't think C&V2 is quite up to the high standard of vol 1 but still the value/money ratio is hard to beat!

Well Phil how did it go?

A K-01 upgrade COULD be made with interchangable mounts one giving direct use of K mount lenses as currently, and another containg a focal reducer similar to the metabones speedbooster which would give the 35mm equivalent FOV with FF lenses. Designed properly AF etc would still be available, and a real benefit of the mirrorless system would be seen.

IMO it needs a viewfinder too, and the looks...