Originally posted by clackers Low contrast behaviour is another thing - have you seen a focus chart like those used to determine those ratings? That's made up of very distinct black and white shapes.
Yes, I agree regarding focus charts and -ev ratings.
Now, when I look at the photo posted here (the one with the guy and the two dogs), the fence is in focus and the person+dogs aren't in focus. K3 AF firmware behavior (as I just checked on my K-3): if the camera does not find a focus, it turn the focus ring up to nearest focus, that's the default behavior of Pentax AF (that's also the default behavior of Canon cameras, at least): the camera AF tries to focus on the object under the selected focus point, closest to the camera.
If the fence is in focus, and the person's not in focus, I bet multi 27 points AF Auto was used, and if this is the case, the camera AF focuses on whatever looks more contrasty since there is no other condition for the camera to know what to focus on. For portraiture, AFS single point select should be used, eventually 9 points Auto, but never 27 points Auto. If any AF mode is selected, that's not really a problem of the camera, that's a problem of knowing what focus mode should be use for each case. Unfortunately, the documentation of the K3 AF is not very explicit, which may also lead to customers thinking the AF is worse on the K3 compared to previous cameras, the truth being that at least the AF of the K3 is more complicated.