jeff OMeara said:...... I have alot of trouble trying to get colour in my stars. Any advice or suggestions would be most appreciated.
Hi Jeff,
Neal gave you good advice when he suggested longer subexposures. As a general rule, lots of white stars in an image would suggest star saturation. As you can see from what others have done:
http://www.robgendlerastropics.com/NGC7023NM.html
http://www.tvdavisastropics.com/astroimages-1_00000f.htm
there isn't a lot of color in the surrounding stars. Shortening the exposures won't gain you star color and it will only increase the 'noise' in the rest of the image.
The graininess in the outer portion of the nebula would also suggest longer exposures .
When you are faced with an area that has both colored stars and faint areas, take two sets of exposures. A short set that captures the stars without saturating, and a longer set that gets good S/N on the faint stuff. Then just layer and paste the colored stars onto the longer master.
Someone also suggested using a sigma combine (or something similar) to get rid of your outliers. That is good advice, too. CCDStack has the most sophisticated data rejection routines that I have found, but even a simple sigma will work well (assuming > 8 subs).
dan
P.S.
I almost forgot one of the most important points.
Don't touch the white point as you did. That will certainly make stars whiter. The only thing that I would do with a levels adjustment is set the black point. The midpoint slider is kind of a heavy handed adjustment. You have much better control of things by using a curves adjustment.
