I've added a colour layer to my M51 from last month. Still not entirely happy with this object - still some slight collimation/tracking issues.
Captured in k3, stacked in registax 3, coregistered and colour balanced in IRIS. Final re-combination and curves in Photoshop.
Exposure Details :
IR Block 91x15s on 200mm @ F5 with SC3.5
IR Block 69x31s on 200mm @ F5 with SC3.5
IR Block 120x15s on 200mm @ F5 with SC3.5
Red 40x15s on 200mm @ F5 with SC3.5
Green 40x15s on 200mm @ F5 with SC3.5
Blue 40x15s on 200mm @ F5 with SC3.5
Curdridge Observatory, Southampton,UK