Strange phenomenon I noticed with my D90

[danizer]

I was at kitsilano beach a few days ago with my friends and decided to record a 720p video of the sun setting. I recorded 20 minutes worth of sunset in 4 parts (cuz HD video is limited to 5 minutes each). When I was putting the clips together in Vegas, I noticed that half way through the 3rd clip the images get brighter despite the sun setting lower.

The only thing I can think of is because its in video mode, the camera attempted to compensate for the amount of light decreasing...but what else could be the cause for this and anyone have any idea how i can prevent this from happening in the future?



the image on the right is a screen cap after the sun gets lower

[dhillon09]

disable auto iso?

[moky]

if your video mode has manual exposure setting, that might help out a bit.

[Nismo200SX]

Holding AE-L AF-L button will lock the exposure setting when you're shooting, so panning from a bright window to a dark corner won't screw up your carefully constructed ambience with a quick lighting change. (Of course, manually panning and adjusting your focus will probably mess up the shot anyhow.) Reader TimmyTimeTravel just told me about this article, which contains an additional AE tip: "To set your camera for AE-L (hold): Menu > Custom Settings (Pencil Icon) > f (controls) >> Assign AE-L/AF-L Button > Ae lock (hold) > Ok"

from Gizmodo http://gizmodo.com/5055525/nikon-d90...-and-the-shaky