I've now had two occasions when AF just suddenly stopped recognising people and just grabbed focus towards infinity.
- Shot 1: Night Time Dinner Celebration. Was working just fine fine as the dinner guests were walking around (or when panning/zooming) with a box getting drawn around and focus switching between subjects in the frame. The camera was setup in the corner of the room with the 28-135 High Base, wide focal length and with auto iris (but F4ish most of the time). At one point (during the speeches) all of a sudden all the focus boxes disappeared from the OSD and the FX6 was focused on a background light. The speakers were maybe 5m away. Thankfully I was behind the camera at the time so could manually rack focus.
- Shot 2: Daytime memorial celebration. It was lightly raining and overcast. All was working as expected while panning around and zomming in/out on the crowd. It was initially fine while filming the speakers during the formal part, then focus boxes all disappeared and focus drifted out towards infinity. The speakers were under a tent so in even more shadow and had some highlights from the sky behind them. 28-135, low base with auto iris ranging around 5.6-8 and it was fairly wide to get both the memorial plaque and the speakers (who were again around 5m away) in frame. Again, just jumped into MF.
The commonality is low light and the fact they were both long static shots (you know how speeches can go on!). Any thoughts on the cause / how to mitigate?
Thanks
Nathan
- Shot 1: Night Time Dinner Celebration. Was working just fine fine as the dinner guests were walking around (or when panning/zooming) with a box getting drawn around and focus switching between subjects in the frame. The camera was setup in the corner of the room with the 28-135 High Base, wide focal length and with auto iris (but F4ish most of the time). At one point (during the speeches) all of a sudden all the focus boxes disappeared from the OSD and the FX6 was focused on a background light. The speakers were maybe 5m away. Thankfully I was behind the camera at the time so could manually rack focus.
- Shot 2: Daytime memorial celebration. It was lightly raining and overcast. All was working as expected while panning around and zomming in/out on the crowd. It was initially fine while filming the speakers during the formal part, then focus boxes all disappeared and focus drifted out towards infinity. The speakers were under a tent so in even more shadow and had some highlights from the sky behind them. 28-135, low base with auto iris ranging around 5.6-8 and it was fairly wide to get both the memorial plaque and the speakers (who were again around 5m away) in frame. Again, just jumped into MF.
The commonality is low light and the fact they were both long static shots (you know how speeches can go on!). Any thoughts on the cause / how to mitigate?
Thanks
Nathan
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