I've taken some images of faint asteroids that require 300 second exposures, and obviously I get a certain degree of blooming in most images. However, on images where there is a particularly bright star that star will have a black streak through it. Somebody did tell me that the CCD reading around that star will reset to zero if there is too much light or something, but can someone maybe elaborate on this? I mean why does it do this? I've really only encountered the "light spillage" appearance from overexposures where there is a streak of light on the image.