Strange lines no idea...help?

[stephen99]

Hi guys. I have an Atik 420 mono and optolong filters. Its on a celestron edge hd8 and Hyperstar. No idea what this weird graident is. Driving me nuts. I over exposed it a bit to show whats going on. Help?

thanks.

Steve

[eyegore]

Stephen,
 I owned an ATIK 420C and also saw these artifacts. It seemed to me to be chip-related, as rotating the camera did not change the orientation of the bands. I did not go so far as to clean the actual surface of the chip itself, just the window, but flat frames seemed to eliminate them. Since I observe in a very dense urban area, my images need stretching more than at less light-polluted skies, so the bands were very troublesome, and I traded the 420C in with some other equipment for an ASI1600MC cooled camera for wider field applications.
 I now have an Atik 428EX mono, and though it shows some non-uniformity, it displays much more even density across the chip and I enjoy that unit greatly.....excellent sensitivity.
Neil