An example of basic image processing

I have only recently delved into astroimaging so my skills compared to some of the experts are fairly limited at the moment. However that is part of the fun of this hobby in that you pick up tips as you go on and you learn with practice.

I have included an example of some very basic processing on a monochrome image of the Horsehead and Flame Nebula to show how the images appear on your computer screen when they are downloaded from the camera and how each stage of processing makes a difference to the final image. I hope this example shows that some very pleasing results can be obtained in very little time with limited skills.

The example used here is using the Starlight Xpress SXVF M8C single shot colour camera. The images were taken using 2x2 binning mode which means the effective pixel size is 4x normal making the camera 4x as sensitive as it is in it's native mode but it also means that the colour doesn't work due to the way the built in bayer matrix filter works. Focusing was done with Maxim DL but without the aid of an electric focusing unit on the telescope so it was manually focused while monitoring the laptop screen and focusing analysis dialogue box in Maxim DL (this makes focusing much easier but plenty of time and care should always be taken over focusing as it is very difficult to compensate for any errors in the processing stage). Simple automatic dark frame subtraction was used in Maxim DL  so before the images were taken an exposure of 200 seconds with the lens cap on was taken first and this dark frame was automatically subtracted from the subsequent exposure frames with the lens cap off. No other calibration was used. In a lot of circumstances even dark frames aren't always necessary and this is particularly so with Starlight Xpress cameras which are good at handling noise. No filters were used either and no autoguiding was used in capturing the images.
As a follow up to the first example of basic processing I have now included the processing workflow for my latest image of the star Sadr in Cygnus including the nebulosity surrounding the star. This image was taken with the Starlight Xpress SXVF H36 which is a monochrome large format camera with 16 million pixels each 7.4 microns square. A 12nm Hydrogen Alpha was used made by Astronomik. With emission line imaging such as Ha longer exposures are needed so the exposure time was 10 minutes for each subframe. As before focusing was done manually using the two stage focuser on my TMB 115, it is important to note that focusing must be done through the filter you are imaging as I have tried with and without and there is a marked difference between the two as to where perfect focus is. Simple autodark subtraction was used in Maxim DL and as before no autoguiding was used.