A I have tried to use darks with the Qhy268c just made the image worse so I don't bother - also flats, if the optics are clean and you have little in the way of vignetting, maybe not necessary depending on the total integration and number of frames stacking particular at the size and format of images posted on most web sites. Granted if you are creating images destined to be an APOD or win a major competition, go for it, although there are numerous ingredients which determine the quality of the final product one of which may be flats
