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Yes, will definitely avoid double stars in future!
I managed to get out again last night to fine-tune collimation further. This time I didn't use the dew heater to prevent internal currents. It seemed to have helped a bit. Humidity was a bit higher (78% vs 45% the previous night), but managed to get about an hour outside, before the corrector started dewing up.
I focused on Hadar/Beta Centauri and primarily used the 15mm EP to do the collimation. I tried again with the 6.7mm EP, but found it a bit hard. Is this to be expected? When I read the collimation discussions on Cloudy Nights etc. they all suggest using high power EPs to do collimation. But I struggle with anything under 10 mm. The patterns are simply too wavy/all over the place to make any meaningful tweaks. What am I doing wrong?
After collimating, I had a good look at the Jewel Box (NGC 4755) nearby. Although I couldn't see anything via naked eye (thanks to suburban light pollution in Sydney), I could clear make out the stars via the telescope. There were dozens of stars all clearly resolved and I could easily make out the different colours as well - white, blue and a prominent yellow star in the middle. Is this about as good as it gets with a well collimated SCT? Or can I eek out a bit more performance?
Please let me know if you have any other tips to improve collimation. Looks like I will have one more clear night tonight in Sydney before the clouds roll in for the next week or so!
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