X-H2S subject tracking miss

Truman Prevatt wrote:

Morris0 wrote:

Greybeard2017 wrote:

Morris0 wrote:

What I'd love to see is someone photographing a challenging subject such as swallow tails in flight over grass or water with things growing. Take a bunch of images with subject tracking on and also with it off and compare the hit rate of images with the subject in the frame.

Morris

Here is my bet - if it was me then I would get a higher hit rate with subject tracking on - if it was you then it would be a higher hit rate with subject tracking off.

:-}

I was shooting swallows in flight yesterday and had about 50% of the in frame birds in focus. Of the ones that were not in focus, it was divided about evenly between nothing in focus and focus on the background which was long marsh grass. If subject tracking is working properly, I'd expect less focused on the grass. If it is working great, then many more should be sharp.

I was shooting off an elevated walk over the marsh and observing the swallows flight patterns. When I saw one that was going to come within range, I'd pick it up and 1/2 press as soon as it's in frame. Then start a burst when I felt the bird was sharp. As they are super fast, there is little time between each step and I suspect sometimes I'm fooled into thinking the bird is sharp. One thing that has always amazed me about Fuji cameras is they will track an out of focus subject and keep it the same amount out of focus. With my camera set for focus priority, it must think it's in focus.

Morris

One possibility in your case is unlike a DSLR with cross point AF points - the Fujifilm AF is a hybrid of non-cross point PDAF points and CDAF. It uses a combination of the two. Given the type of target you are considering on the XT3 with a slower update rate than the XH2S is led to your issues. If the contrast combination of measurements from contrast and PDAF phase difference dominated that of the birds - the grass would have have grabbed the AF and might have dominated until the bird provided great phase difference. So I think it might be the lower read out speed of the sensor and the PDAF points of mirrorless are not as robust as the large cross points in the dedicated PDAF detector of a DSLR.

I'm actually doing the best I ever have with swallow tails since gestating the 500 MM PF.  Much better than I did with the Sigma 150-600 Sport on my D500.  Both lenses have blazing fast focus and I'm slowing down.  I never tried the 500 PF on my D500 for swallows, I can only wonder what would have happened.

It's complicated and making sense of in the field work is super tricky.  Thank you for the analysis Truman.

Morris