X-T5 autofocus problem

I borrowed my nephew's new X-T5 to try birding with a used XF 100-400 I just bought. I let him use my OM-1 + PL 100-400 in exchange. I set shutter to mechanical + electronic, AF continuous, focus mode "tracking", subject detection "bird", and high speed burst at 15 fps. SS 1/2000, camera nearly always set aperture to f5.6, auto ISO (between 6000-12800)

I find the camera has problem with autofocus on dark colored birds eg. red-winged blackbirds - the "bird" detect white frame seems to pick up the bird quickly and correctly by enclosing it, but somehow autofocus refuses to latch on (either no green frame, or OOF inside green frame), sometime even when there is no confounding background such as marsh grass (eg. a bird on a stump against clear sky). I have to coax autofocus by moving to the adjacent tree bark (a high contrast object easy to focus) to bring the focus closer to the bird, before moving back to the bird to acquire focus. I have tried both autofocus ranges on the lens ("full" and "3m - infinity") with no difference.

There is generally no problem with white birds eg. swans, or birds against clean background eg. on water. Once autofocus latches on eg. swans taking off, there is generally no problem with tracking (except my bad panning ... currently practising!)

I checked that the camera has the latest firmware 1.03.

Has anyone experienced similar problem with their X-T5?

Not with an X-T5 but with its corporate sibling, the X-H2. You need to set up one of the assignable buttons to toggle Subject Detection on/off; you will definitely need to disable it in a number of cases and just fall back to Area or Single Spot AF; I recommend Area AF. Especially for dark objects against a lighter background.

IMO the Subject Detection methodology is in its infancy at Fuji.

Thanks. Yes you are right: once I noticed when I switched from "bird detect" to ordinary spot AF through the quick menus, autofocus on the bird (central object in the field) is absolutely no problem.

I have no experience with the X-T5, but in general I get more keepers on Fujifilm bodies when tracking is turned off, and I adjust the AF settings for my current scene / requirements.

Try my X-H2s BIF settings:
www.fredmiranda.com/forum/topic/1772910/0

I've had reports that they work with the X-T5.

Also, read this regarding a way to thin about what subject detection dose:
www.fredmiranda.com/forum/topic/1801321/0

Also, if you are new to birds in flight, it takes a lot of practice.

Morris

Thanks for all the suggestion. The X-T5 is not mine (and my nephew does not own the XF100-400... yet) but I shall pass on the information to him. It is also very useful for me to learn on my X-T30.

P.S. To Morris: what about "pre-AF" and "eye detect", are they necessary (I am asking this more for X-T3/ X-T30)?

I don't have the XT5 but the XH2s. I now use a small af point with subject detect.

This allows me to increase the number of af points from 117 to 425.

For smaller birds this should provide a better hit rate with the bird subject detect turned on.

If you haven't already got it set it up this way then I suggest you give it a whirl.

Cheers
Paul