Thx folks,
That's a nice result from the Dob Jeanette and I will go ahead with the 2.5GSO given yours and Adrian's comments.
As to CA correction I have been following other threads discussing the relative merits of CA reduction via filtering.
http://www.iceinspace.com.au/forum/s...d.php?t=117179
and various archived material here and cloudynights etc.
Trevor