Here is one of my older sketch. This is a digitized sketch of Beta Orionis. In order to create a digitized sketch like this one, I have to draw 2 separate pencil sketches at the eyepiece. The first sketch is a wide-field lower magnification one and the the second sketch is a zoom in one; showing diffraction rings. These 2 pencil sketches act like base for me to work in Photoshop.
In Photoshop, I first process the wide-field sketch; using layer to create a dark background and using Brush Tool to re-draw the stars. Another minor things I add are the glow of some bright stars and diffraction spikes. With that I am done with the first sketch.
For the second sketch, I also create a layer for the background sky and using Brush Tool to re-draw the stars. But the hardest part has to be the diffraction rings. The diffraction rings in the sketch have to be as realistic as possible. For this I create multiple circular shapes surrounding the star with the size of the first circle smaller than the next one and so on. Using the combination of Clone Stamp Tool and Brush Tool to recreates the appearance of the diffraction rings through the eyepiece. Add some glows and diffraction spikes and the digitized sketch is finally done.
For anyone who is interested in this double star here is its information on Stelle Doppie website:
Mag Pri: 0.3
Mag Sec: 6.8
Separation: 9.42"
PA: 203.6
Hope you enjoy the sketch and thank you for reading and Clear Sky as always 
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