Hi TingTing, My imaging train is a modded Canon 100D, a relatively light DSLR, fitted with a Skywatcher coma corrector. Also using an Astronomik CLS clip LP filter. Thinking of switching this to a Hutech IDAS P2. The thing is.......the filter is about the same price as the 130 PDS......seems the wrong way round but there you go. As you can see, I am still plagued with gradient and focus hassles. I've been using DSS and Photoshop CS2 and running the Gradient Xterminator trial. For galaxies and clusters it works reasonably well but for nebulae I seem to fall into deep kimshee. Star colours are coming out ok but I seem to muck up on curves and levels and colour balance. Take the M81/M82 shot, for example. My individual subs clearly show a red hue in the middle of the M82 "cigar shape" structure. After stacking and histogram stretch and saturation shift, I seem to lose any red in the finished image. Never mind, I'm learning a lot and loving the journey. Thanks to all in this forum for their inspiration ad tips, re balance. In time I'll switch to guiding and EQMOD and CCD but for now I'll keep learning my ABC and times tables, so to speak.