I knew frankenstein always had it in him, under all that rust, dints and cr4p it was a diamond in the rough.
Quote:
Originally Posted by Kunama
Great work on the collimation Marc. Looking forward to the images to come.
I received all the collimation kits and adapter this morning in the mail so I will revisit for sure. The scope is cooling outside as we speak, everything is set up for a night of imaging or two, as sunday is looking good too..
Need to still fix collimation for stars. I can do that tomorrow as I've received all the collimations kits this morning. Field looks sharp and flat though with no noticable curvature or flaring corner to corner.
Need to still fix collimation for stars. I can do that tomorrow as I've received all the collimations kits this morning. Field looks sharp and flat though with no noticable curvature or flaring corner to corner.
Yes Marc - they look very good from edge-to-edge, very nice indeed.
Yes Marc - they look very good from edge-to-edge, very nice indeed.
Cheers
Dennis
Looks a lot better than the mewlon 210 because it's a classical cassegrain and better corrected. It was fairly easy to collimate accurately today. The newtonian side I did struggle. Got it in the end but it was pretty hard.
Last night was great for testing. I had a couple of hours before clouds rolled in from the west and there was also a thin moon crescent to play with.
I had used the TAK scope the previous day to finish collimating the cassegrain focus. It's very close but still needs a tiny more tweaking which I'll do with the artificial star. I spent some time on the moon visually from 32mm to 24, 9, 6 and 4mm eyepiece. I could still easily snap to focus with the 4mm eyepiece and see some very nice sharp details. A lot more than with the C11. I took a couple of shots with my SONY NEX-5 and ZWO ASI 120MM.
Then I switched to the newtonian side which was a bit of a disaster. Visually the focus point snaps and the image is very sharp as well. The fov is huge. On closer inspection at higher magnification I can see very obvious astigmatism so the detective work is starting. I suspect something to do with the secondary as the primary is ok in cassegrain mode. There is an aluminum cylinder that encases the secondary glass to stop it from dewing up I assume. It was very tight so I've losen that. I think maybe it was pressing against the glass. The astigmatism can be compounded by the fact I still haven't got the newtonian side collimated correctly. But there is definitely some kind of stress in the glass there.
Here' s a couple of shots of the primary collimation push/pull system, centering and locking mechanism. It's well designed and very simple.
Some good progress. Finally got everything collimated tonight including the newtonian side. The aluminum shroud for the secondary was stressing the glass and causing the distortion. Losening the screw that holds it did the trick. There is a very slight sign of astigmatism when very close to focus but nowhere near what it was. I don't think it will be and issue with the CCD given the image scale as it is so close to focus, might not even notice it. Will see when I do a full fov shot. I also tested the newtonian corrector. Seems to do a decent job. Will post before/after pics later on.
This is the diffraction rings for the newtonian focus IN/OUT. First part of the video with the SONY NEX-5 , second with the 120MM.
I did a star test on both cassegrain and newtonian focus tonight taking advantage of the steady skies. Went down to a 4mm eyepiece and I didn't have to tweak either. Spent a bit of time on the moon, saturn, NGC 104, the tarantula, anything bright enough that I could see from my light polluted skies. So I think I'm done and dusted now. As Diego would say, I am happy.
Video of the moon tonight with the SONY NEX-5 at the Newtonian focus. No corrector.