irek83, the composition of your mountain bike photo and the equipment used to shoot it reminds me of an AF test I performed with my K-3, on 2nd Jan 2014, soon after I bought this camera. My son was into athletics, so late in the afternoon we went down to the sports ground of our local school and I shot some Long Jump with the K-3 and a Sigma 70-200/F2.8 HSM II. Since it was late, we got straight into it before the light level dropped too low.
1/1000s, f/3.2, ISO200 128mm FL
Here is a 100% crop
I did not apply much sharpening as I did not want the jumper's outline to look too "digital".
Here is a shot of a run-up before reaching the line and leaping off. I've applied more sharpening and played with the contrast levels a bit.
1/1250s, f/2.8, ISO160, 105mm FL
Here is a landing shot. It was late in the afternoon and we must have entered the "Golden Hour". The sand, as shot in this shot, was quite yellow.
1/1250s, f/2.8, ISO125, 105mm FL
I adjusted the WB when I developed the raw to match my recollection of what colour this sand normally has.
Which of these two versions is more "correct" probably comes down to taste.
I've shot a lot of week-end and competitive athletics with the K5 & K-3, using both a Pentax DA* 60-250/F4 & the Sigma 70-200/F2.8 HSM II. I found with Long Jump that it was hard to get all the shots in a jump sequence in focus. Depending on how close I was to the edge of the sandpit and what FL I used, the change in closing distance over time when the jumper was in the air and just before they landed was the most likely time for shots in the burst to go OOF. I'd say this is caused by the limitation in how fast these general-purpose lenses can make big focusing adjustments. Strangely, the landing itself was more likely to be in focus, probably because the jumper's forward speed drops dramatically soon after touching the sand, and the AF has a little extra time to get the final shot(s) of the burst back into focus.
Dan.