Hi Debbie, For my flat fields I put a large white cardboard target on my observatory wall and illuminate it with an X-mas tree light placed down near the floor such that no shadows are cast on the target. At the end of an imaging session I shut the roof, turn off all the interior lights except the tiny one and point the scope at the target with the imager and focus positioned and set where they were during imaging. Then I shoot whatever length exposure is needed to come up to about half what is needed to saturate the chip. Patrick astrodeb@charter.net wrote:
For those of you that do CCD imaging I was wondering how you take the flat field frames. I've heard that that a twilight sky makes a nice flat frame but the camera has to be focused first. Without stars to focus, this is quite difficult.
I was going to try putting some printer paper over the dewshield but I filled up my memory card before I had a chance to try it. SBIG recommends a white T-shirt. Has anyone tried this before? I'm looking for ideas how to incorporate flat field frames into my images to remove dust and other artifacts that accumulate on the lens.
Clear Skies,
Debbie