[raymo]

A combination of several things I think Glen; a little bit of CA possibly, as
the lens was wide open [trying to gather as much light as poss before the moon rose], a bit too much contrast tweaking, and the colour saturation
was also a bit high, looking to see how much exposure was necessary to
start to show the reds in the area.

P.S. It turns out that I was wrong on all counts. Every sub I took that night, anywhere in the sky, has strong blue halos around
all the brighter stars. I hope I haven't bought another lemon, this model of lens is not supposed to have any C.A. at all.
raymo