Thanks to everyone who responded. I've now managed to get it to work. It was all about distance and separation. Once again many thanks.

Thanks for that Doug I'll try your suggestions in the morning

Good point. Being relatively new to this not sure what separation distance should be but my attempts are sharp front to back over about 15 yards. It's getting a bit dark now but will experiment tomorrow. Thanks.

Thanks Doug. Done all that and not working. Definately a Pentax FA 50mm. Beginning to look like I have afaulty lens.

Thanks for that.I can set to f1.4 but background isn't blurred. I'll try doing as you say and clean the contacts.

Thanks for that Jonathan but I've got it locked on the "A" setting. Does the bit about the lens pulling out and pushing in mean anything to you?

Just treated myself to a new lens,smc PENTAX-FA 1:1.4 50mm. Thought from various reviews it would be good for portraits. I've got a K10D and another couple of lenses but I can't figure out how this 50mm works.Can't get it to shoot blurred background at f1.4 on either automatic or manual settings.Manual says focusing ring should push out and pull in for autofocus or manual focus but I can't move the lens at all. Any help would be very gratefully received.