Karl-Heinz can you post some in-focus small crops of a few frames and some out-of-focus areas in the same frames?
I'm just concerned that the 19mm Sigma at that distance is getting so much in-focus the evidence of actual tracking isn't clear.
Compare with Don Parrot's recent doggie post on DPReview where his choice of lens, distance and aperture makes everything completely obvious.
Thanks for the question. Good points.
So how do I know that the camera tracked?
Well, once the E-M1 has achieved initial focus in C-AF TR mode it indicates the area with a green wire rectangle in the viewfinder. Keeping the shutter pressed and requiring focus for taking another picture, a new green wire rectangle will appear in the next frame as well. And so on. I saw the green wire rectangle move with the car across the entire frame although the camera was stationary on a tripod. All I did after the initial focus was to keep the shutter pressed down.
Another test for continuous AF tracking is to focus on a certain object, like an apple on a tree, or the label on an hummingbird feeder. Then rock the camera gentle back and forth. The green wire rectangle will try to stay on the initial object. In this test the E-M1 is much more successful than the E-M5 as it stays focused on the initial object much longer.
Please, try it if you have any of the cameras.
BTW, C-AF behaves quite differently. Keeping the shutter halfway pressed while slowly rotating the camera, then briefly pausing, rotating again, etc the camera will focus on whatever it is currently pointed at.
I hope this helps. Thanks again for your question.