I think these lenses may just be pushing the technology beyond its limitations.

I hear some of the old 500mm "drainpipe" lenses aren't bad? Not stellar but you won't find much else for the money at the same focal length and the results are pretty decent. Usually they have a preset aperture and no coupling to the camera, the mount is generally a T2 interchangeable one so you can fit them to most cameras.

Well, it's my Dad's and I'm not 100% sure when he bought it! Will ask later. It exhibits the same faults on his K-7. I'm pretty sure it's under 12 months old but he's definitely had it for more than 30 days.

I've tried updating the K-m firmware but no change. The DA 35/2.4 (which I keep on the camera) snaps into focus and locks on every time in the same lighting conditions.

Well, the 150-500mm here definitely isn't right then!

It won't lock focus without a lot of fiddling about. It actually goes past the right point then stops and flashes the green hexagon as if to say "I'm stumped, you try!"

I have read about similar problems with other brands of camera which were solved with firmware updates, but I've no idea how to do this with a lens. My K-m is fine with everything from the DA* 50-135mm to an old F 35-70mm, and focus confirm works perfectly with lenses going back to the original K series. I therefore think it has to be the lens.

Anyone know how long the Sigma guarantee is?

£65 is about on the money, although I'd be more inclined to have one of the two businesses John named do the work.

If it was just the light seals then you can replace them yourself, takes about 20-30mins of careful, methodical work but it's not especially complicated. The kits are around £7 including postage from the USA and contain everything you need aside from a solvent to clean the old glue out - lighter fluid or something alcohol based will do.

Do not use any form of solvent on the focusing screen (or scrub it) as it will ruin it! Let a professional sort that bit out.

It has to be Dracula. He vants to suck your batteries!

The main problem I have with the Bigma is that it won't lock focus at 500mm. The bulk doesn't bother me too much aside from the fact that trying to hold it steady and focus manually is a bit of a tall order and I generally find a tripod handy.

Not a camera fault as both bodies tested are fine with a selection of Pentax AF lenses, I think it's due to the f5-6.3 nature of the beast. I know my K-m is fine with an f2.8 zoom in any lighting conditions, switch to an f5.6 and it can end up hunting unless you have a contrasty subject and good light. Newer bodies may be better as I would assume Pentax have upgraded the AF sensor to go with the wider ISO range (not a lot of point in outstanding high ISO if the thing can't focus in low light).

Same here on the remote.

The third party one I bought is identical to the Pentax IR one in operation but I find I use the self timer instead. Two or twelve seconds gives plenty of time for any shudder caused by my pressing the button to calm down, and the mirror lockup helps too.

I can't fathom the B setting at all though. On my film bodies it's simple - the shutter will remain open for as long as the button is depressed. I have used this pretty extensively while shooting night scenes and infra-red with a cable release, timing exposures with the second hand of a watch when the camera's shutter speeds don't go slow enough.

The K-m only has an IR remote option but try as I might I can't fathom how to make it keep the shutter open. I've tried the suggestion that pressing once opens and again to close (no dice) and obviously tried holding the button down.

Try a cheap teleconverter with the glass bits unscrewed?

I did this with an old Jessops TC which had the A contacts but produced terrible images. The A contacts still work and it's more use as an extension tube!

That sounds not unlike a Canon IP90 I used for a while. The ink cartridges were about the size of a matchbox.

I think the real xmas postal scam is how deliveries suddenly take twice as long and items seem more prone to going walkabout. Not as if they haven't had the entire history of the postal service to get used to dealing with the extra traffic...

I just hope the light-fingered individual who presumably made off with one of my parcels last year was suitably annoyed when they found it to contain a battered old ERC rather than anything resalable!