Perhaps you haven't noticed, but an Astrophotography Forum was just recently created. You would most likely get the best response posting this question over there. Perhaps one of the moderators would move it there for you.
>One of the >things you do is to make a series of dark flat images, which >are 1/4000 ISO 100 exposures with lens cap and eyepiece cover >on.
I believe you are referring to a dark frame subtraction, if so it should be taken at the same ISO and shutter speed the regular frames are captured at in the same ambient conditions. But something sounds amiss. At ISO 100 and 1/4000th, the D80 should have provided a black frame. Could you put up an example somewhere for us to analyze?
>* Paint Shop Pro X2 does not open the Nikon D80 RAW format >correctly.
Perhaps, the NEF is a proprietary format that third party software companies reverse engineer. So all raw converters are not created equal. Another thing that makes the D80 less than desirable is that it suffered from considerable amp noise plus most Nikon DSLR's are known as star eaters requiring the Mode 3 work-around to eliminate the median blur filtering of the NEF long exposure.
>* I should convert Nikon NEF to some normative RAW format.
In MHO, not really. The only real reason most give is to convert to a more universally supported standard to insure you will always have software that will open them. Trouble is there really isn't an industry wide standard yet. Adobe has been pushing its DNG, but it's not been adopted as Universal yet. >* There's a tiny elf in my camera lighting a firecracker when >I take the image.
I hate those tiny elves when they get into the camera, the should stick to making cookies!!