Originally posted by HenrikDK Here is my first question: Is this fairly normal? I have had the camera for about 5 weeks, and did think there were quite a few pictures that were softer than I had hoped - but always figured it was just me...
BF/FF is not uncommon with DSLRs of any brand. It's how tight the manufacturing QC is. However, OOF doesn't automatically mean BF or FF. Pentax DSLRs have wide area AF sensors which might cover more than you think. They tend to be attracted to higher contrast target regardless of distance. That means if the background has higher contrast than the intended target, it will AF on the background. Sadly unlike some Nikon DSLRs, there is no option to alter this behavour (like forcing it to pick the closer target) so you just have to know how it behaves and work around it.
Originally posted by HenrikDK Second question: Following the instructions, I was taking pictures of a test chart just a few feet away. Can I expect the same adjustments to work when the subject is much further away?
I have calibrated my own Pentax DSLRs and from what I have learnt, calibrating AF based on printed chart is flawed because the shooting distance is too close. A simple explanation is that turning the focus ring 1mm near infinity will have far greater impact on focus than near 0.3m. I suggest fine tuning the AF based on daylight target at least a few metres away. Also, AF is inconsistent even when properly calibrated so make sure to repeat the tests many times and obtain an average result. When the camera/lens nails the distant target well, it should be fine for closeup.