Quote:
Originally Posted by skwinty
Hi Peter
Thanks for detail.Could you give some idea of calibration procedures applied for this shot.ie dark, flats etc.
|
I continually update both my dark and flat library, as the closer in time they are to the data frames , the better the calibration seems to be.
For flats, median (i.e at least 3) combined sky flats are essential. Aim for about 1/3 full well capacity. Move the scope around a few degrees from flat to flat.
Darks with a temperature regulated astro CCD are pretty easy. Just match the temperature and time of the light exposure. Again use about 3 or more median combined to avoid cosmic rays producing black "holes".
Also make sure you use the same focus, filter and camera orientation for any of the above (yes...*a lot* of work) and even then when shooting from urban areas smog, haze etc. will conspire to still give gradients.