Today was “Sports Day” at Anthony's preschool, which is a fun event full of play, silliness, and dance. Like last year's Sports Day, it was very hot — 90s in the shade, but the entire event was in the sun — but this year I think the heat was worse for my camera than for me.
I was using my big 70-200/2.8 zoom and Nikon D200 on my monopod. After taking about 830 pictures, I was surprised to see the “battery empty” symbol. This surprised me both because I expected to get more shots from the battery (I can go weeks without having to change a D200 battery), and because there was no “battery getting low” warning in the viewfinder for the previous few-dozen pictures.
I swapped to a new battery, and after taking a shot, the camera again shut down with the “battery empty” symbol. This was highly distressing, because I knew the battery was full.
I was eventually able to figure out that if turned the camera off and on, I could get a few more shots before it happened again. The battery most certainly wasn't low, as I was able to get 400 more shots with it this way, and even after that, the “Battery Info” menu item still reports that it's 70% full.
When I got home, I posted about it on a Digital-Photography-Review Forum, and it was immediately suggested that I had Dead Battery Syndrome, something that I hadn't heard of.
No one really knows what causes it, or what makes it go away, although there is a lot of speculation involving all kinds of things.
For my part, I slightly suspect that it's the lens overheating. (As I said, it was hot, and the sun was unrelenting.). Two hours after I got home, I pulled the lens from its carrying case, and was surprised to find that it was still decidedly warm. The carrying case is padded to the point of being an excellent insulator, I guess. Anyway, I put it on the camera and after one shot I got the “empty battery” symbol.
Yet, five minutes later — five minutes in my hyper-air-conditioned office — it was fine, and it's been fine since. I wonder whether I'll run into the problem again, and if so, when. It's an uneasy feeling.
[Update: a user with a similar-sounding issue with his D300 thinks it's related to dirty electrical contacts.]
Although I took 1,207 pictures today, sadly, I didn't get anything really great like last year. Hopefully when I give a second look through, I'll find a few keepers....