Questions tagged [collimation]

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3 votes
0 answers
81 views

Why can’t I get a red dot instead of spread out light when collimating the primary mirror

Using a laser collimator, I have centered the dot for the secondary mirror, but all I see is spread out light when I go to adjust the primary mirror. Shouldn’t I be able to see a dot, and move that ...
3 votes
2 answers
137 views

Is a mirror cell only necessary for collimation?

I'm building a truss Newtonian, and I'm planning on achieving collimation using turnbuckle-style trusses, as demonstrated in this thread. If I'm collimating this way, is there any reason to support ...
6 votes
1 answer
1k views

Telescope collimation issue

Recently, I purchased a Chinese 8 inch reflector telescope from local store. When I observing stars and planets I've been having trouble getting really sharp image from this telescope. I observe Venus ...
7 votes
2 answers
28k views

I'm having trouble achieving sharp telescope focus

I've been having trouble getting really sharp focus on my telescope. Using Saturn as a reference, with a 20mm eye piece it is very sharp. But when I go to 10mm or 6mm, it gets bigger and blurrier. I ...
5 votes
0 answers
70 views

What to do in case of concentric circles that are not aligned with the cross after collimation (Picture inside)?

I have been collimating my newly bought first Newtonian telescope for a few days now, but I can't get the center of the circles to align with the intersection point of the spider's reflection. I have ...
1 vote
1 answer
626 views

Celestron C14 collimation and cleaning

When checking the collimation of a Celestron 14" SCT I took this image: My question is: how much will the particles causing the local aberrations affect the image quality? (i.e. do I need to ...
3 votes
0 answers
184 views

Precise meaning of collimation/alignment of a binocular

My question is about what exactly is meant by a binocular being collimated/aligned. I'm familiar with optics in general, but not with the nitty gritty of binocular design. There are various resources ...
2 votes
2 answers
2k views

What are the aberrations of an SCT? And how can they be eliminated?

The Schmidt-Cassegrain telescope is amazing! It is compact, suitable for astrophotography ,and it requires little to no collimation. However, the SCT has some inherent optical issues. What are they? ...
2 votes
1 answer
2k views

collimating AstroMaster 114

I've owned my AstroMaster 114EQ for about a year now, and feel like I know my way around pretty well, but I'm only just becoming aware that collimation is recommended. The user manual has instructions ...
4 votes
1 answer
597 views

Can a Ritchey–Chrétien telescope be collimated using a standard Newtonian laser collimator?

Is it possible to use a standard Newtonian laser collimator, such as this one to collimate an RCT? If so, is the procedure any different than collimating a Newtonian (i.e. make the laser go into the ...
3 votes
1 answer
260 views

Newtonian reflector collimation question

After an initial collimation, I took my scope (150mm/750mm) out for a star test. While I could see concentric circles when the bright star is at the centre of the video, when the star is on the side ...
2 votes
1 answer
2k views

Collimating with a home-made collimation cap

I've made a home-made collimation cap and am trying to use the procedure linked to in another answer. However, I've run into two issues right off the bat. In this picture from the linked page, it ...
2 votes
1 answer
926 views

Laser Colimator vs Cheshire eyepiece [closed]

Both the laser collimator and cheshire eyepiece are tools used in astronomical telescope collimation. What are the main advantages/disadvantages of each? Which one might be best suited to start with ...
1 vote
2 answers
988 views

Laser Collimator producing oval not circle on the Primary

I own an orion laser collimator which I had not used in a very long time. I decided to collimate an old Celestron NextStar 114 and I realized that the laser did not produce a circle but an oval. ...
9 votes
1 answer
8k views

How can I accurately find & apply the white donut to the center of my mirror?

I have a Plettstone 18" Dobsonian telescope and use a Howie Glatter tuBlug, laser collimator, and Square Grid Projection Attachment to adjust the mirrors. Proper collimation requires an accurate ...
0 votes
1 answer
238 views

Laser Collimator For Dobsonian vs Newtonian

Will a laser collimator like the Gosky 1.25 Metal Laser Collimator, https://www.amazon.com/gp/product/B01M4IVUYG/ref=crt_ewc_title_dp_1?ie=UTF8&psc=1&smid=AHQ6VCR020F8X, work for a dobsonian ...
21 votes
1 answer
15k views

How can I collimate a dobsonian telescope with a laser collimator?

I've had a dobsonian telescope for a while now, but I've never been able to collimate it. I thought I had it collimated once, but when I looked through it the star didn't look right, it looked kind ...
3 votes
1 answer
109 views

Collimator for Dobsonian, same as Newtonian?

I have been looking on line for Collimator for my Meade Dobsonian. The only Collimators I can find are made for Newtonian Lenses. It's a 8" mirror with a 1.25" lens. Will this work for my telescope?