hi there Rodger and Bart
thank you so much for the reply it sounds easy enough so I will give it another go because I am using a ccd camera with a mechanical shutter I will have to keep the exposures long enough to get rid of the shutter shadow would this mean I am restricted to taking them at night not sure of the exposure time I should be using with this camera the Sbig 8300c I do collect my lights in RAW and my darks as well so this should be the same with flats and debayer in the processing is that correct many thanks again
cheers Pete
