Hello + quick question about a lense please!

So why not spend big on new lenses? The k-m is a great little camera, but all your Pentax lenses will fit your new K-7 when you up-grade!

If cleaning the contacts doesn't work, send it back. I know of one forum member who has this lens and would probably sell it, so post a Wanted advert if you want a replacement. But you should be able to meter using the aperture ring in manual mode - you need to close the lens down with the optical preview (presuming the k-m has one!) and adjust your shutter speed accordingly.

I believe it is a nice lens, supposedly sharp wide open, and will deliver shallow DOF on close up subjects. Example: link

But unless you are after 'environmental portraits' the 50mm would be better - you should be able to meter in manual in the same way - or use the kit lens.

Sigma lenses may not report correctly to the camera anyway, so it's no surprise that an old one doesn't.

For an important shoot using the kit lens would be a much better bet for you, especially at first.

Old lenses are best left to experiment with at your leisure, not under time pressure.

If you haven't already got a kit lens... ring Chris at SRS Microsystems
It won't be that much more expensive compared to the lenses you already have, and a lot more versatile (and probably sharper too!)
Matt

hi all. i have the kit lens too, so can always photoshop to declutter the background if i can't shoot outside. so i have two back up options... was gonna use it on its wider angle to get some group shots of some other things, but i think i'll get the portraits too just to be safe.

for the record, the supplier i bought the sigma 28mm A from is meeting me later to swap it, with choice of 50mm and 80mm (or something similar) so fingers crossed!