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Getting put out with my reflector...


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I have an Orion XT8 and when its properly collimated it can offer some good views, but thats the problem it rarely seems to be properly collimated. Try as might I can never seem to get it perfectly aligned. The stars seem a little fuzzy, or pixelated for a different term. I like to view a mix of deep sky and planetary objects. I was thinking of switching it up and branching out to a good refractor telescope. I was just wanting some suggestions as to what to do. Maybe just keep trying to nail down the collimation problems. All in all I want something I can browse the skys with.

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Is there an astro club near to where you live, if so give them

a call, they will help you to collimate your scope, once you

see how it's done you can do it yourself, also it's good to

see it done hands on.

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I don't have the xt8, but I do have the 8" OTA they use on gem. The optics on these are actually above average. Going by Suiters star test, the mirror seems to be between 1/4 - 1/8 wave. When I first got the OTA, the spider was waaaay overtightened, causing the vanes to skew. I then purchased a Howie Glatter Tublug and laser. It got me collimated extremely well, as you can also use it to align your secondary. Align secondaty with focuser first. Make sure you can see all 3 mirror clips through drawtube and secondary should look round with the reflection. Get centered on dot on primary. Finalize collimation with primary. The Tublug/laser combo is fairly pricey, but it did wonders on all my newts.

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Plus, how has the weather been in Alabama? Hot and humid as usual? That will kill your views also. It has been fairly humid here with the monsoons. Lately it has been around 45% humidity, with 95F temps at night here and it will wreck your view a bit. Don't give up on the newt yet. Like Peter said a refractor with the lightgrasp of a *' newt, will set you back a bit. Heck, just make an aperature mask and you will have a .50 cent/ 60mm APO.

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Thanks guys! I get easily disgusted with it because after Im done collimating I would sweart its almost perfect... take it out and I can tell its just not right. But I will pick a Saturday here soon where I have plenty of time and set the scope up on a table so I dont have to bend over and get on my knees, and really give it a go.

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just a couple of points. are you allowing enough time to cool down/warm up depending where it is stored? a scope this size needs about 40-60 minutes before it is at its best.

centre Polaris in the field and turn off tracking etc. defocus very slightly, until the star doubles/triples in size, no more. are the rings concentric both sides of focus? if not then the collimation will be out.

newtonians are as good as anything on axis but as scopes get faster, coma does make the stars less like points off axis. the faster the scope, the closer to centre this happens. it's not a problem, just one of the characteristics of the design. for truly pinpoint stars refractors are (I have to admit) slightly better than newts but the advantages of newts over other designs, to me, outweigh the disadvantages massively.

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Not to rule it out but wonder if you got a bad eyepiece in there somewhere and that it is not just collimation alone. I guess you would know if they are doing it if they all struggle, it is the collimation. Interestingly I had a friend come over first time few weeks ago who I did not realise was into a bit of astro ( but very casually ) he brought an eyepiece that he suspected was poor for an old frac he owns and asked me to try it, I don't recall what make it was but I tested it in my scope and it did not look good. Not an expert in testing eyepieces by any means, but when I rotated the eyepiece the astigmatism moved with the eyepiece as I did the in and out of focus test ( as I rotated it in the focuser ), this suggests that perhaps it is poor, badly made, or a badly figured lens shape. My own eyepieces do not do this. Anyway I gave him my old stock 25mm to try at home and see how he fairs.

Anyway just to throw the thought into the pot.

Edited by AlexB67
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  • 2 months later...

Thanks guys! I get easily disgusted with it because after Im done collimating I would sweart its almost perfect... take it out and I can tell its just not right. But I will pick a Saturday here soon where I have plenty of time and set the scope up on a table so I dont have to bend over and get on my knees, and really give it a go.

I have a new XT8 and yes, working on a table with it is a lot easier than on the floor.

I just collimated mine last night and could actually see the quarter moon this evening. I came across this site:

http://www.smartavtweaks.com/RVBL.html

They describe a neat method of collimation, but it entails having a laser collimator. I bought Orion's LaserMate Deluxe. At first the red dot was exiting from the front of the scope. I thought this isn't good… but after only a few minutes and some minor tweaking of both mirrors, I got the dot in the bull's eye.

Don't give up. It's just a slow, tedious process  :)

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