The D700 has a high-frequency “ultrasonic” vibration dust removal system. The camera wiggles the low-pass filter in front of the sensor at a very high frequency to dislodge dust particles. Many people don’t realize that the sensor itself is not exposed to dust. It is covered by the filter, which gets dusty over time. A dustremoval vibration system is expected in this class of cameras these days. Let me quote Nikon’s website:
“Dynamic integrated dust reduction system: Self-cleaning ultrasonic sensor unit minimizes degradation of image quality due to dust particles.”
Sounds good to me, and it seems to work pretty well, too!
In addition to the vibration cycle, the filter is coated with a tin oxide coating that is antistatic in nature and helps prevent dust from sticking to the sensor.
I’ve read articles that claim this is not particularly effective in some cameras. All I can say is that since I’ve had my D700 I’ve only seen one dust spot on a series of pictures. I had just come back from the beach and expected to find lots of sandy dust on my sensor. However, I found only that one tiny spot.
I immediately fired up the vibrating dust removal system and then made some test shots. The dust spot was gone. That’s been my total experience with dust and the D700. Since that time, I have my D700 set to clean the sensor on startup and shutdown.