#7. "RE: colourful dots on picture during long exposure D800, please help?" In response to In response to 0 Thu 15-Nov-12 05:05 PM by cbrandin
These are not hot pixels (mostly), rather it is a long exposure noise - which is a type of thermal noise, not stuck pixels. Colored spots are to be expected because in order to get white dots all three colors (RGB) would have to be noisy in equal amounts. Thermal noise affects pixel wells individually - that is, red green and blue pixels are affected separately.
The "long exposure" noise reduction feature can be used to mitigate this to a large extent. However, when you use long exposure NR images take twice as long to capture because there is the actual exposure and then an additional exposure taken with the shutter closed.