4K still camera recording stops occasionally after about 8 seconds.

You are all convincing me that the card is really too slow.

If you look at the bottom left in the box entitled "4K" you will see a tiny asterisk and on the back of the package is a small note saying, "4K video recording operation may vary depending on the devices you use . . . "

I believe my FZ300 is around 96MB/s whereas certain Lumix dedicated camcorders shoot 4K at around 45MB/s.

I suspected it might be something like that but it has only ever failed that way with the first clip I have started shooting, so I am nowhere near any 2GB limit.

It occurred when I first got the camera and tried to shoot a 4K clip on a new card.

The SD card warning came up and I mistakenly assumed I had accidentally bought a slow card . . . until I pressed the record button again and everything worked perfectly.

I suppose a workaround might be to start shooting long before I need to or shoot a dummy clip first but it's hardly ideal.

Yes, it is supposed to be though it is at the lower end of the recommended speed range.

As I wrote that first sentence another idea popped up . . . I believe the camera records VBR and the panning shot of the aeroplane was surrounded by trees and bushes with countless leaves and small details.

Quite possibly the complexity of the image was similar to filming snow and confetti causing the bit rate to increase beyond the capability of the card!

On the other hand, when it first occurred when the camera and card were new, the scene was a simple static one with the camera on a tripod.

You are probably correct in implying that the card is borderline.

Hang on! I'm confusing megabytes with megabits.

My camera shoots at 96Mb/s which is 12MB/s.

The card reads up to 90MB/s so presumably writes around 45MB/s, so it should easily accommodate video shot at 12MB/s.

So it isn't necessarily the card at fault. Maybe just some other glitch at work on odd occasions.

Yes. I can shoot for as long as I want. Obviously not half an hour or so but 10 or 15 minutes cause no problems.

That's a good point. I can't remember because it was nearly 3 years ago . . . and before anyone suggests that the card is now old or well used, let me add that this also happened when it was new.