Originally posted by derekkite No. I have a 150-500 sigma, but didn't use it. A faster focusing lens may help closer in, but I suspect that this is the limits of the body. The second to last shot was back focused meaning that the dog was running faster than the focus logic could adjust.
I doubt this is the body. Lens moving mass/inertia, AF (in the body or in the camera) motor torque & total focal movement distance are probably more significant for these bigger zoom lenses than the body AF processing. AF predication isn't exactly rocket science. There should be enough subject-to-background discrimination with the new high-res AE sensor and the denser, high-sensitivity AF sensor array to provide sufficient input data for the AF processing. I would expect firmware revisions to polish the tracking ability further.
My experience with AF performance photographing Long Jump with the K-5. 3 different lenses:
Pentax DA 55-300/F4-5.8 https://www.pentaxforums.com/forums/115-pentax-k-5/115277-k-5-sports-photogra...ml#post2409556 Pentax DA* 60-250/F4 https://www.pentaxforums.com/forums/115-pentax-k-5/115277-k-5-sports-photogra...ml#post2410088
Sigma 70-200/F2.8 https://www.pentaxforums.com/forums/115-pentax-k-5/115277-k-5-sports-photogra...ml#post2410938
Because I couldn't trust the K-5's Auto AF performance here, I usually used centre-point focus. Sometimes the jumper moved above or to the side of the centre and AF went OOF because of the fixed centre-point. It would be good to try this with more effective AF.C tracking.
However, I think other focus problems are the result of the lens not keeping up. I plan to get the K-3 sooner or later, so it will be interesting to repeat these tests, in a more standardised and careful way with all 3 lenses, to see if the lens is the limiting factor in this running-towards-the-camera situation.
Dan.
Last edited by dosdan; 11-18-2013 at 03:47 PM.