For me, Kevin, cluster and nebula need differents processes. With cluster the information is concentrated in small areas, as dots.
To get a good shape of stars and color information you need a very good camera.
With the same set of equipments, mono camera will show better quality of stars. The Airy disk wil be an Airy disk.
If you analyse with attention and zoom a bright star with color camera, you will see three areas: the nucleous, the Airy disk
as an extention of the nucleous, and a border normally with more strong color.
This distortion is caused by the bayer pattern of color cameras. See my posts in
http://www.iceinspace.com.au/forum/s...00#post1109100
The real size of pixels of color camera isn't the nominal size. For example: for Canon 1100D or T3 the bayer pattern RGBG will be converted to a color information RGB. Therefore, for Red information the Red pixel will have a virtual size of 20.72 microns: Rxxx Rxxx for RGBG RGBG . The same to the blue channel.
If you compare the Red and Blue channel with Green channel, you will see that the stars are larger than the stars in Green channel. Mainly if the star is very bright. Independent of the color of star: blue, red or yellow.
What I didn't understant, yet, is: why the Red channel of Canon has the largest size ? The excessive noise in this channel has something with this issue ?
With my Halfa filter I feel that there are black holes between the red dots informations. As the virtual red pixel size is large, and real pixel size is small... it works like if the pixels are assembled with long distance between them.
Something alike this representation (independent of number of pixels in the sensor):
mono camera:
R R R R R .....
note: R for a luminance dot.
color camera:
R____ R____ R____ R ......
note: R____ for a RGB color dot.
