First, I also have a K20D, so I know how the camera can hunt from one end of the range to the other, especially in low light and low contrast objects. Now my K200D (second hand, but only a few months old and still well under warranty) has a couple of times shown a different kind of hunting. These occasions have been in a fairly well lit enviroment and also while focusing on a non-extremely-low-contrast object. The camera does not hunt slowly from one end of the range to the other, but goes very fast like zak-zak-zak-zak-zak, 2 or 3 times a second as long as I try to get a focus. Then trying again, perhaps on a different spot, the camera has managed to focus normally.

Does that sound like a hardware problem and if so, is it a problem of the body or the lens? Atleast once it was with kit zoom II, probably both times. The lens has a multi-coated Hoya UV filter on (mostly useless, I know...) Could it be a contact problem between lens and body? I assume this is not something that K200D does normally, as my K20D doesn't do anything like this. Could the filter cause this, although I have never experienced this with the same lens on my K20D?

It looks like the camera's definitely defective. Now it seems to work like that constantly, with different lenses and a fresh set of Eneloops. Off to warranty repair it goes...

Off to warranty repair it goes...

And after nearly a month, I got it back. And the bloody thing's acting up the way it was before the "service"! Way to go, Pentax service.

Luckily this is my secondary camera, but I'm not happy how this is going.

[rawr]

If you tell the camera to set the focus point to the center of the viewfinder [Rec mode > Select AF Point > Center] does the same behaviour recur?

Otherwise what you are describing sounds like pretty standard camera behaviour when on 'Auto' or 'Multi' AF mode as it tries to decide which of the 11 focus points to use.

My K200D makes similarly very quick, snappy AF moves as it jumps from point to point trying to decide what to focus on but does still focus fine on something.

I use 'Center' mode to tame the AF's hyperactivity though, especially for confusingly varied subjects (birds nestled in between several layers of foliage) or low contrast or low light subjects.

Thanks, but I have my cameras on center AF always, so that's not it. And the problem is intermittent. For a while the camera focuses quite normally, that is it locks on high contrast objects quite easily but hunts slowly from one end to the other on low contrast objects and in low light. Then all of a sudden it starts this fast "pumping" and can't get a lock on anything, no matter how good the light or how high the contrast is. And I've never experienced anything like this with my K20D and the same lenses work flawlessly on it.

I've contacted the service again. Let's see what they have to say. They probably want to keep the camera on their shelves gathering dust for another month and then send it back again.

The plot thickens. First the unlucky camera was for four weeks in service and they had obviously done more or less nothing to it. Back it came and I had to send it there again with a lens. This time it took about two weeks and they said they had changed an AF sensor and that the problem seemed to be gone. Well, that's what I thought at first too. But during the first days it has started presenting this problem AGAIN. Like when I for example try to focus to some dark low contrast object and it is naturally unable to get a focus, the camera every now and then goes again to a state where it can't focus on anything, even a bright high-contrast lamp. Going to the menu and exiting cured it this time.

Oh boy. What use is a second camera body if it's more being serviced than used! And the thing is that while my K20D is a better camera, I've found that I actually prefer this K200D due to its form factor and size.