Flat frames made easier

I've always had problems with flat frames, especially using MaximDL with my CCDs. The main issue was finding the correct exposure time, because a poor flat frame is worse than no flat frame at all !
Therefore, I often skipped flat frames and used post-imaging processings, for instance with background extractors, which is difficult and not always satisfactory.
Now, I am using ASIAIR Plus and it is a game-changer. Why ? Because the micro-computer calculates itself the right exposure time for your flats, by analysing the provided light in front of the telescope.
So, in a few seconds, you get a perfectly balanced flat frame, that you can use directly with ASI DeepStack (a bias is needed), or any other stacking application.

Philippe

I have used MaximDL since 2005. I have always used it to create flat frames and do calibration. Depending on the camera, you must keep the Max ADU below a certain nunber. Starlight Express advised below 20,000 for there CCD. They may have changed that number for latter models, which I have, but I just remained with lest than 20,000. Many imagers use 30,000. I now use a QHY268M (Sony IMX571). I processed my 1st images with it and used the 20,000 Max ADU cut off. They worked fine. The reason for not letting the ADU go over a certain ADU is to keep the flat frames liner. I do not use, are have never used flat darks. The exposures are too short for darks, they will be in fraction of a second. I only do bias flat substraction.

It is time consuming to set flat times up in Maxim. You must fine the correct exposure time for eash filter. But, one that is done you can save that filter set up and simply apply the flat filter set up to each session. Assuming you maintain the same white light intisity. I use the Optec Alnitak flat panel.

I have also use Sequence Generator Pro to do Auto flat calibration with the 20,000 ADU setting. It worked well. Since I do all my calibration in Maxim, I prefer to set up flat filter exposure in Maxim to maintain consistent FITS files documentation.

For whatever its worth, Lynn K.

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