Explore Scientific Coma Corrector

[Bart]

Hello All

I got the ES CC some time ago but for one reason or another never got around to sorting it. Well, not quite true. I stuck it in the focuser some time ago and realised I was short of inward focus. Did some research and realised I needed to bring the primary forward. That was a bit of a job, with a 16" mirror, but completed that some time ago. Anybody wants some tips on does and don'ts, just ask......

Anyway, last night was clear but with a moon, which was perfect. I taped a white plastic bag (well, a bit of one) across the top of the CC, screwed the helical top to about hallway, and adjusted the focuser to project an image of the moon onto the plastic 'sheet' until it was in focus. When focus was achieved, I locked the focuser. Then I inserted my most inward focussing EP (20mm 100* ES) into the CC and focussed it using the helical top. It had to go in about 6 mm. Stars nice and sharp all across the view. I then inserted the ES 14mm 100* and found the point where it was par focal (almost) and locked it with a parfocalizing ring. Did the same with the ES 9mm 100*. Ran out of time but can't wait until a clear night happens next to see exactly how good I got with parfocalizing all three. It does make a significant difference but looking forward to a moonless night to really see the effect and the ease of switching the EPs. I expect some small amounts of refocussing with the helical top, but it should be relatively small. The 9 and the 14 needed to be moved by about 8 or 9 mm to parfocalize. I was pleasantly surprised how easy it was to set up, as I thought there would be an amount of faffing around. Don't know how many people use the ES rather than the Paracorr but I'll report back when I've got a chance to use it for real.

Barry

[Davesellars]

It'll be interesting to hear how you get on with it!  I was looking at this when a second hand Paracorr came up instead.   the par-focalising rings sound like a good idea.

[John]

Good to hear that there was not too much faffing around after the faff of moving the mirror up the tube.

 

[spaceboy]

I wanted the ES HR CC for a while but when I got wind of focusing issues I took a side swerve. I mean what a performance having to adjust the primary up the OTA. I mean you would have thought ES would have done their research on the most commonly available scopes before releasing the CC. I'm sure there may be a ES HR CC mk II out at some point.

I too like the idea of parfocal rings. Where did you get the 2" from Barry?

[Bart]

I got some from Sky's the limit in England and scope stuff in the US Spaceboy