Are there huge differences in the ability to focus in low light between different brands and models?
I have a Pentax Kx with a Sigma 30mm 1.4. My problem is, that the camera's autofocus does not work in low light, even when a picture with manual focus turns out ok*. I accepted that and mostly use manual focus at night now.
But last week I was in a bar and a girl had a Nikon and was shooting all the time. It did look like she was using autofocus and I assume she wouldn't have continued if the photos did not turn out. Unfortunately I did not get to see the exact model of the camera or the lens. Is it possible that here autofocus is so much better?
As I understood the first answers, my options are to upgrade to K5 or K7 for 800$ or sell my Pentax stuff and buy a Nikon or Canon with new lenses for 2000+ $? Changing the options in my camera or buying a different lense will not help in my case.
Would it have been wiser to buy an entry level Canon/Nikon and then 400$ on a lens with a good autofocus?
* I just tried in a unlit room of my house with 1.4, 1/30s, 1600 ISO, which produced a photo with EV=-3, but autofocus would not work.