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Hi, I got a skywatcher skyliner 200p dobisonian a few days ago, my first observing session was out in the cold and the telescope dewed up when I bought it back in. I then noticed that the glass on the base of the telescope(not the primary mirror inside) was smudged and had a little ring shaped scratch on it. I tried cleaning with a lense cloth but it is still slightly dcratched and smudged. Does anyone know if this makes a difference to the inside primary mirror?
Hi, I know that there has been a couple of threads on how to collimate a newtonian, more specific, how to center the secondary mirror under the focuser.
I bought mine "Concenter eyepiece" for almost a year ago and can't praise it enough - it makes centering the secondary a breeze.
Have anyone else tried this? What is your opinion?
I have also read that some have questions of how accurate it is? - I might not know the answer to this question, but what I do know is that after I have been centering the secondary with the Concenter eyepiece, I finish of the collimation with the Catseye XLKP and Blackcat. The small adjustments I have to make of the secondary after adjusting it with the Concenter eyepiece tells me it is very accurate. It is just the absolute finest adjustments i have to make afterwards.
I have made a video of how it works and how it looks like when I am collimating my scope. (10" f3,4 astrograph)
Best regards, Daniel
It figures! First clear night in ages and the pollen is as thick as..well, something really thick. Up to now, I have been fairly careful to avoid dust getting down the tube, but pollen is going to be unavoidable for the next several weeks.
So...what does one do? Are there some do and don't things I should be aware of? It looks like my mirror comes out fairly easy (SkyWatcher 10" ). I'm guessing "chuck into the dish washer on the pot scrubber setting" is probably a really bad idea.
What then, is the plan? What chemicals/detergents should be used...or maybe all chemicals should be avoided? Is it a no-touch surface? Is there perhaps some magic spray that one uses? I do have a can of electronics air that I plan to use from a safe distance to persuade away loose pollen, and that may be enough for the present.
I am thinking on grinding my own lightweight mirror (first f4 16", later f4 24"). The lightest and cheapest option is to get a thin blank and slump it in a decent kiln.
Anyone has longer term experiene with slumped mirrors? Overall doesn't seem to be more work than a normal (not pregenerated) blank.
Do I have to grind the backside as in case of normal flat back mirrors to avoid astigmatism? How do people support a convex back while grinding? Does it make sense to grind a hole in the middle for additional support? I am remotely considering a convertible Newtonian/Cassegrain system anyway...