Originally posted by jacamar
I have tried Audiobomber's approach but can't make it work for me. I have difficulty locking the centre focus point onto the subject, then I just have a bunch of red dots fluttering around it and out-of-focus shots. I find it easier to lock on with spot focus, though it doesn't work 100% of the time.
A bit more explanation is warranted here.
When you half-press the shutter in Expanded Area AF-C mode, the camera tries to find focus on the central point. As soon as focus is confirmed, you need to take the shot. If you don't take the shot, the camera assumes that it has selected the wrong target, and starts to search adjacent points. When you take the shot, the camera records the shape and colour of the object in focus and begins tracking. It tracks until you let up on the shutter button.
If you have accidentally focussed on something other than the subject, say a cloud in the background, that is what the camera will track. If this happens, you need to stop and restart tracking by letting up and re-depressing the shutter button. This is called focus bumping. Sometimes the camera loses focus during a sequence. This again calls for focus bumping. IME, the K-3 is very good at tracking with the settings I listed above, and given a fast focussing lens like the DA*300 or 55-300mm PLM. Tracking a BIF with the older 55-300mm lenses is possible, but you will have a lot more missed opportunities.
https://www.pentaxforums.com/forums/38-photographic-technique/332226-focus-h...ml#post3806571