Hi all,
Shot the comet last night in windy conditions with cloud causing lots of frames to being useless. This was taken with 24mm lens at F2, and Astro 40D at ISO 400 with 8 minute exposure. I wanted to try some 12 minute exposures, but cloud arrived. I should have had the comet further to the right in the FOV, as the tail extends out of the frame being over 36 degrees in length. I notice a fork tail in the thumbnail with one extention going above Canopus.
I have just taken flat frames for the first time, with a piece of white cotton material over the end of the lens, pointed at the sky. Using the same F ratio,focus and ISO as last night images. Standard exposure with histogram central, took 10 frames and added them into the mix for DSS. The result seemed to reduce the vignetting very well.
http://i638.photobucket.com/albums/u...s/dc10a80c.jpg