Celestron 925 EdgeHD Hyperstar
Canon T1i modified by Brent Oliver
Uncle Rod Uncle Rod's Astroblog: http://uncle-rods.blogspot.com/
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I put aside the other half to spend frivolously.
Quote:Thanks RodI have a few questions:1. Can collimation be afected if the corrector plate isn't perpendicular to the optical axis of the telescope? If it can, how do I make sure the corrector is perpendicular?2. Is it correct to get the central obstruction centered with the adjustment of one knob? I ask this because at some point I thought I had it collimated but when I tried to focus the stars, I couldn't (obviously the telescope was not collimated). I used Sirius all of the time and the tracking always kept it on the FOV (very high in the sky here in Bogotá since we are 4.8 deg North and Polaris is too low when you can see it). Software was PHD and the images were 1 sec taken with a SSAG. Is that an ok procedure, or should I do something different?3. I made the process working with the Celestron f6.3 focal reducer. Would it be better to use the telescope at f10 or even at f20 with a barlow?4. Using a star implies that I will have to wait for the next clear night. I could use a point light of the red illuminator of the finding eyepeice at low intensity inside the house, a few meters away of the telescope. Will this produce good results?I know thes are a lot of questions but I really need some help on this matter.Thank you in advanceAlfredo
"A telescope is either good or cheap, not both" - but sometimes you get lucky!
Quote:This method (vernier) is not as accurate. If the central baffle and OTA are not concentric, or if there is some tilt in the system, it will not result in a properly centered secondary.Another reason why the star test is so important. It is very sensitive and will allow for very quick and very accurate adjusment.Not saying that the caliper won't work in all cases, becuase it might get you close.But the star method can get you reliably close every time.The reason I know is that I have encountered this before. My C5 can have the secondary perfectly centered using a vernier, but show decentering at the Poisson Point (with the resulting apparence of secondary mirror shadow decentering when out of focus). The only way to get it centered was using a star.Not saying it is not worth a try to use this method, but I would rely on the star test to confirm it...
Refractors Reflectors Two Cats A few eyepieces
Quote:4. It can. Usually it's easier with a star. A very small pinhole works best, but yes, you can do that.
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