Hi,
I'm using an A7r4 with subject tracking AF. Although the camera is not new to me, it's got around 450000 actuations on it from doing repro work, in its retirement I've taken it for personal use. I've never really used it for AF before though. My last real AF experience is from the 5D3 many moons ago as a pro event shooter. Since then and for repro work I strictly use manual focus.
I've tried the tracking subject AF with AF-C and was really impressed with it but this was using the Tracking Expand Spot mode. It was also using my wife's 16-50mm in crop mode for testing, stolen off her A6000.
Fast forward and I bought myself a VIltrox 50mm f2 Air. I've been very impressed with the images I've seen from it on this forum and wanted a small 50mm.
Did some testing last night taking some static photos of the kids at home.
The tracking subject AF does not seem to be all that good. In indoors lighting it was very often backfocusing or choosing background subjects if they were more contrasty. I switched to Tracking Spot S which but again the focus was mostly backfocused. I changed AF Tracking Sensitivity to 'Locked On' and Priority Set in AF-C to 'AF'. The latter helped but what helped the most was simply changing to Flexible Spot S and moving the focus point to the subject rather than using the tracking mode and recomposing. Seemed rather counter intuitive as this is hardly an advance from the DSLR days. The 'tracking' thing is supposed to be the Sony party trick.
Is this simply a combination of 3rd party lens, f2 and low light? Is it that Tracking in general is a tool which cannot be relied on for accurate focus wide open on an older generation of camera like this and a more modern generation camera would be more accurate?
I'd appreciate your thoughts!