Since the launch of K-r and K-5, it has been widely reported that this latest SAFOX IX/+ AF system of Pentax is really problematic in AF accuracy under indoor environments and particularly with tungsten lighting.
It is even found that the AF accuracy of the K-5 deteriorates sharply for a moderate lighting level at EV8 (which is not really quite dark actually) as measurbated by someone. As for the K-r, previously Pentax mysteriously withdrew the new 1.01 firmware from their Japanese global support page, which was not by accident, but intentionally.
Pentax Germany even admitted before that the K-r has the front focusing issue under lower/tungsten light and committed that a new K-r firmware would be released. However, a month has elapsed now and we only see today a new version of the K-5 firmware is released at the Pentax.jp English global support page:-
"Changes to V1.03
- Improved the accuracy of auto focus in low-intensity light condition.
- Improved stability for general performance."
As for mysterious K-r disappearance case, after weeks, the K-r 1.01 firmware has been re-uploaded and re-published at the Pentax global support page again. I quickly downloaded it and re-installed the "latest" in my K-r to see if there is any hidden improvement. What I first did was to check about the actual and exact firmware version. Below is what I learnt with the PhotoME:-
Original shipped K-r firmware:
Last mysteriously withdrawn K-r firmware:
Latest re-uploaded K-r firmware:
So, Pentax guys at their HQs actually put a previous version of the firmware for the K-r but not a newer one, which is just very head scratching plus disappointing afterall! >:-( I have made a quick check about the indoor AF accuracy with the "latest" firmware 1.01.20.08, though. See the pair of test shots below:-
(AF Fine Adjustment Disabled)
(AF Fine Adjustment Enabled and at the Maximum Value of -10)
Lens used is a DA 16-45 at 45mm and f/4, focused at an object at about 1m away, the DoF is not that shallow actually. Central AF point was used, AF-Single mode; No re-composition of the frame.
Still, as you can see, the problem is the same and it is persistent. The camera Front Focused in indoor tungsten environment. An adjustment value of -10 will make it (as usually) and a sharp picture could be obtained.
Two Yet Unresolved Major Issues of the K-5
Magnified AF Errors of the SAFOX IX than the SAFOX VIII !?
SAFOX IX Tungsten/Yellow Light Front Focus Issue Fully Investigated
Ten Reasons for Thinking Twice before Decided on a K-5..
K-r AF Point (Mode) Selection Firmware Bug