EdgeHD 8" - Second light

[Stu]

A very quick second light this evening, mainly just wanting to check a couple of specific things out.

Being a little OCD about image shift, I have fitted a Baader SteelTrack focuser with Steeldrive. I had been considering a Feathertouch, but this came up in the classifieds and is ideal. As a first step this evening, I extended the focuser 14mm which is about halfway down its range, focussed using the SCT focuser then locked the mirror. There may be eyepieces which need a different range to this but I will find this out as I get more time with the scope.

The new focuser works very well, image shift is a thing of the past, and fine focusing very easy without vibration of the scope. Much easier than before.

My second issue on first light was star shapes which I put down to cooling, as the collimation seems pretty good. This evening I put the scope out as soon as the sun was behind the trees. I took the diagonal out, and angled the scope at about 45 degrees down to allow the hot air out through the back and vents. It had around two hours cooling before a quick half hour session at around 10pm.

Results tonight were much better. Whilst not totally 'refractor like', the stars were much tighter to the point of being completely acceptable to me. It is only really on the brighter stars that there is a significant difference, diffraction patterns a bit messier and less well defined. I'm assuming that with the additional optics in the Edge, it is not possible/worthwhile to use a cooling fan in the visual back?

Test doubles were Mizar, Alberio, Epsilon Lyrae, Pi Aquilae and Delta Cygni. Obviously the first two are trivial, but still looked lovely, star colours in Alberio in particular.

All the others split with little difficulty. Pi Aquilae is the tightest but was no problem. Delta Cygni in particular was very nice to see again, I love the tiny secondary being resolved so clearly.

Last little test was M13 and M11, just as a comparison against last night. The sky wasn't quite as dark, and I'm down 2" in aperture tonight but was still very happy with the views. The dimmer stars were resolved very tightly, the only thing lacking vs the 10" was a little brightness.

I use the scope tonight on my Giro-WR mount on the EQ6 tripod. It was pretty solid, although the movement was a little jerky, a heavier counterweight would sort that out though, no problem.

So, very pleased with the scope and happy with how it is working now. It is a great option for getting more aperture to a dark site and that's something I intend to do more of this autumn/winter.

Stu

[RikM]

Sounds like a successful evening Stu