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What an incredibly frustrating night

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#1 John59

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Posted 21 November 2012 - 09:14 AM

Last night I decided to use the SCT (C11) and was looking forward to a night of videoing Jupiter. After full setup alignments and going back and doing the “all star polar alignment”, I was ready for action.
I noticed the collimation was off and decided to use the video camera to assist in adjusting the collimation. In short, I made it much worse. The screws were hard to turn. To the point that I thought they were all the way in and no “in” adjustment was left. So I backed them out just a tiny bit and collimation was starting to look a bit better. As I kept adjusting always being careful to ensure the screws were not getting too loose. The star looked more like a Spirograph pattern. This was getting bad. As I continued to adjust I heard the unmistakable sound of one of the screws “Click” and knew immediately that the one I was on, had disengaged from the secondary. :bawling:
Game over for tonight. There is no way it was going to re-engage without pulling the corrector plate off. No matter how hard I tried, it was not going to happen. With this much work ahead of me, I am going to replace these little Phillip heads with Bob Knobs. Fortunately I have other telescopes to still be able to get out with, but still what a pain. The good thing is that there are plenty of instructions and photos on Cloudy Nights in great step by step methodology making this a tedious but simple recovery. Looks like I am about to get a lot of collimation practice with a SCT. :grin:

#2 Asbytec

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Posted 21 November 2012 - 11:22 AM

Well, if it makes you feel better, we all have those nights. Same stuff, different day. There's probably a reason so much is written in these forums about collimation, replacing this or that, fixing some thing or another. Welcome to the club.

I had a down night, too. Needed one, actually, thankfully is was nothing dramatic. Just could not find the first double star on the night's list. Lost my glasses, they were in the eyepiece case, thankfully. It was dark, didn't see them. And the clouds rolled in.

Last year, a bat pooped on my brand new meniscus nearly fresh from the box. I thought the world was coming to an end. Also got bat poop in my hair and on the finder. Yea, that ended the night, had to ready up on how to clean glass. Goggled "clean bat poop from meniscus" Nothing showed up.

Don't forget to make lemonade. Roll your sleeves up and good luck.

#3 Traveler

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Posted 21 November 2012 - 11:28 AM

Mmmm terrible...I was just thinking about buying a SCT.

Hope you can fix it John!

#4 John59

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Posted 21 November 2012 - 12:30 PM

Traveler,
Don't let my experience prevent your purchase. The telescope has been fantastic for both visual and imaging. This was purely from my own ignorance with being the first SCT I have owned. If I have to end up removing the corrector, it looks simple and I should have everything out and back in the same morning. I have owned several refractors and Dobs and have performed collimation on them without issue. The SCT has a different learning curve and I simply over adjusted. The nice thing about these types of mistakes is that it is easily recoverable and will give me much more in-depth knowledge of the telescope.

#5 dscarpa

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Posted 21 November 2012 - 12:42 PM

Ditto on not letting a unfortunate but rare incident from putting you off SCTs. My 9.25 holds collimation really well unless given a hard wack. I've only had to do it a few times in the 5 years I've had it. I was using it last night with verging on excellent seeing on the Moon, Jupiter and the Orion nebula. At 350X on the Moon and 270X for Jupiter the image wasn't in the least bit soft and the amount of detail was over the top. David

#6 jaddbd

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Posted 21 November 2012 - 03:00 PM

Definitely get the Bobs Knobs. It makes the process much easier and you don't have to tread and inch or so from your corrector in the dark with a sharp piece of metal.

Tip: after you get the knobs on or the old screw back in place, and before it is dark (pre star-test adjustment), you can get suprisingly close to good by looking into the objective from diffent spots between about 5 and 8 feet away and eyeballing concentric circles in the mirrors. The camera is a little off (shaky hands), but you get the idea.

John D

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#7 Rick Woods

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Posted 25 November 2012 - 01:27 AM

Last year, a bat pooped on my brand new meniscus nearly fresh from the box. I thought the world was coming to an end. Also got bat poop in my hair and on the finder. Yea, that ended the night, had to ready up on how to clean glass. Goggled "clean bat poop from meniscus" Nothing showed up.


Bats.
The Pigeons of the Night.

#8 John59

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Posted 25 November 2012 - 11:33 AM

Definitely get the Bobs Knobs. It makes the process much easier and you don't have to tread and inch or so from your corrector in the dark with a sharp piece of metal.

Tip: after you get the knobs on or the old screw back in place, and before it is dark (pre star-test adjustment), you can get suprisingly close to good by looking into the objective from diffent spots between about 5 and 8 feet away and eyeballing concentric circles in the mirrors. The camera is a little off (shaky hands), but you get the idea.

John D


Thanks John!
I will certainly look at this when the knobs get here and I have everything back together.

#9 RichD

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Posted 26 November 2012 - 12:14 PM

Amazing animals though, and keep the moths down.

Unlucky, a frustrating thing to have happen. One of the few drawbacks of the SCT design over the MCT I suppose. I have had similar things happen and normally just give up on the scope, cart it inside to be dealt with in the morning and get out the binos. They never need collimating!

#10 JoeR

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Posted 26 November 2012 - 02:19 PM

I just had a major disappointment with the Hyperstar not being collimated. It is picky at f/2 560mm and it's very hard to tell if it's aligned through the DSLR live view. I though it was good but I loaded the images later onto the computer and saw they were all off just enough to be unusable. 140 subs trashed from really good skies too! :bawling: So I did it the hard way but more accurate by using a laser collimator to align the corrector plate with the allen set screws as close as I could in the daylight, then used a star at night to get it more precise. Now all the Hyperstar set screws are locked down flush and the alignment will be permanent. Of course I had to re-collimate the secondary mirror which was now way off but that was fairly easy. I do not use Bob’s Knobs and it is not an issue with me I just keep a screwdriver in my case.

I once had frustrations like you with a Nexstar 11 GPS that I just couldn’t get right. So I got an artificial star flashlight and that helped. Not having poor seeing from a real star made it easier to get the concentric circles centered right.

#11 bremms

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Posted 26 November 2012 - 11:29 PM

I've been thinking about a way to adjust the corrector side to side slightly. (hence collimating the primary). My C11 is pretty good if I center the corrector. The stock secondary holder isn't really adequate. If plastic, it needs to be glass filled and a bit thicker. Make one from Aluminum.. Like a Hyperstar conversion kit






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