If you have the popup flash open and you press the preview button, the light from the flash comes on and there is a buzzing noise. The light from the flash goes off when you release the preview button. This effect happens on our 2nd D-7000 also. I called Nikon, the technician got a D-7000 and it happened to him also.
His comment was, that is interesting. He has no idea. He will do some research and get back to me.
Anybody have any ideas? Why would the flash come on when you press the preview button? I suspect the noise is from the flash because it is staying on longer then it is supposed to and might be the electronics.
#1. "RE: Curious effect from a D7000" In response to Reply # 0
What you are seeing is a Modeling Flash. This feature is designed to pulse the built-in flash while the Depth-of-Field Preview button is pressed, so you can see how light and shadow falls on your subject.
Check page 228 in the D7000 manual for details.
I'm surprised the Nikon tech didn't know what this was
#2. "RE: Curious effect from a D7000" In response to Reply # 1
I was shooting at a memorial to a recently deceased friend of mine last weekend when this very thing happened to my camera. I didn't know what I might have done to cause it, but I feared that something was awry with my unit. Fortunately, nothing else unexpected happened and I continued taking pictures.