I have checked that. What I think now is that when live view is on, the mirror is up. When you press to focus, it sounds like the camera is taking a photo but there is none. If you press a second time, it seems to work. I think the first press lowers the mirror and the second press focusses tne lens and takes the pic. Does that sound right??

Thanks for that. Just discovered that, with that long lens on, it seems to take a shot, I hear the shutter, but it doesn't actually take any photo and the photo counter in the top screen remains the same. Normally in live view it zzoms in to focus and then takes the shot. It wont do it with the long lens. Any idea about that??

When I attach a sigma 70-300mm DA lens to my new K5 and switch on live view, the camera produces amplified motor noises and also amplifies the sound of my hands moving over the camera. The shop where I bought it has never heard of this and the camera is brand new, with serial beginning 4221. I have read about live view problems and freezing, and that doesnt happen, but the noise problem tells me something is up. Any similar out there? Any suggestions? Thanks