Collimating your reflecting Telescope in just a few minutes

The A&NC’s Ralph Bell shows you how to quickly collimate a Newtonian reflector telescope using a ‘2nd generation’ laser collimator. Presented by Ralph Bell and Robert J Dalby.

Produced by A.R.B Media Productions for The Astronomy and Nature Centre


Andy Gray says:

Thanks for posting this. I Have just bought a new 150mm reflector, my first reflector telescope and couldn’t collimate it with a centering eyepiece. Using the laser i found the primary was so far out I had to fit a longer adjusting screw. Now all is good thanks.

izalahmad says:

Nice video, I have a question. Once I done the collimation and move the focusser (with laser still attached), it’s moving out the hole again. It’s OK?

Hidden Aspects says:

great lesson. may i ask why you need so many globes, though? <)

Kara Rosemeier says:

Thanks, guys – way clearer than the instructions that came with the collimator!

Andre Chesini Okimoto says:

this rocked our world

Gary Simpson says:

Thanks. Seeing it done makes it easier to understand the written instructions.

Tom Ginski says:

hello, I just received my 4.5 inch reflector last week and was quite confused with the enclosed collimating instructions .. am very glad I happened upon your site and Ralph Bell’s very informative and easy to understand collimating video (both of them) .. you two guys are a pleasure to watch and learn from and wished you both lived next door to me .. was sorry to learn of his death .. he was so young.

David Jin says:

Can you tell me that I have a 130slt Celestron on but when I look at stars I see the cross and the secondary mirror in the way while I am zoomed into a star is it supposed to happen?

zytigon says:

Well I read, “pattyvisioncenters” webpage which says,”Type I lasers have a power output of under .4 milliwatts and are incapable of damaging the retina. Most laser pointers are classified as type II or IIIA and have a power output of between 1 to 5 milliwatts. Theoretically, that is enough power to damage the retina……The most common problem associated with laser pointers and the eye is a condition called flash blindness. Flash blindness occurs when the eye becomes dazzled after being exposed to a bright light. Most people have experienced flash blindness after having their picture taken by a camera with a flash. This condition is temporary and most people regain their vision after a minute or so.”

Mr McKillin says:

I collimated my 8 inch reflector using a laser collimator. Got it perfect on the Secondary and primary. Then noticed, when I went to remove my laser, the dot shifted. I began to spin the laser in the lens mount and the red dot proceed to make a circle on the primary mirror. does this mean that my scope isn’t properly collimated?

Pete Turner says:

These instructions are fantastic. I’ve never had to collimate before because I was an SCT user. However, I just switch to a 12″ Dob. Most online descriptions of collimation are mind-numbing. Look to see what kind of an image you have with a collimation cap, do a few tweaks depending on what your image looks like, switch to a cheshire, do some more tweaks, etc. And this is from the sites that purport to have “easy” instructions. I did what Ralph did in the video and it was easy and quick.

Many of the sites say you shouldn’t use a laser. I’d love to know what extra collimation steps could/should be done after the steps shown in this video.

James Drabb says:

This is one of the simplest examples I have seen in years. When I first started 12+ years ago, I wanted a larger dob for the Messier objects. However, My first 10″ dob and a cheshire collimation tool by myself, left me wanting. I actually didn’t go to a star party for over 5 years because I thought everyone would look through one of my reflectors and laugh. I am glad new comers to amateur astronomy have nice guys like you to take the mystery out of (what I now know) such simple things.

If you are looking at the heavens alone, get a laser collimator, and go to a star party. The dumbest thing I did was to think these older more experienced geezers would be mean. It is the opposite. They love sharing knowledge, but they are still geezers!

Haiku Automation says:

great simple easy to understand stuff, TY!

Ryan Arcturus says:

I want to know how to align the focuser to the secondary mirror, any tips? I have a 10inch dob and feel I should be getting better images of Saturn w 6mm and 2x barlow. Any tips would be appreciated.

Jason Bryant says:

“First we’re going to do a shortcut.. we’re going to use a laser.” ….. #thanks =

alfayez a says:

I have 8″ dob skywatcher and it is blocked behind the primary mirror so there is no screws. does it need collimating.

rob b says:

GREAT video , thanks

Jeremiah Gonzalez says:

ya’ll must be brothers?

tillsy23 says:

I no longer fear that word…collimating! I had images in my mind of rendering my telescope useless if I adjusted anything

lucas thornton says:

i was thinking of getting a reflector for my first telescope, i was gonna get the orion skyscanner so i can see the brighter nebulas and galaxies, it has a 100mm aperature and is a table top, i was sure if i should buy this or if i should buy the orion observer 70mm refractor, it cant see the deeper bright sky objects as well though (or so I’m told) kinda stumped a little help?

NM Bowser says:

when i put my laser in and turn it on, it is not a dot. it reflects to the primary like a kind of small rectangle. ideas?

LoneWolf228 says:

I’m having issues with collimating my telescope. I use a laser collimator and I can always get the lasers in the right spots, but the three adjustment screws on the secondary mirror in some way always rotate the secondary mirror to where it puts the offset of my view by about 45 degrees every time. I worked over 5 hours on this telescope and the stupid secondary mirror keeps rotating no  matter what I do!

Through the Telescope! says:

Wow! This makes collimation quite easy to understand, this is very helpful.
Thank you.
Is that the 10″/1200mm?

robert day says:

Can I do this was out a laser ?

jack002tuber says:

This is the best collimation video I’ve seen. I guess you have to have a laser tool to do this then? I can’t imagine how its done without one

Trần Lê Quốc Thuận says:

i with music of chanel and link ;:)

Endo Gamy says:

Hey what are you showing here, Newton didn’t use a laser for collimating purpose.

La4edimension says:

What do you do if you don’t have a laser?

Jon Kennedy Federation says:

I have a NEWTONIAN 150/750 and have collimated it to precision with a laser collimator but STILL SEE crosshairs!

Can you help? What am i doing wrong?

Kurosaki says:

Wait….If you move the primary mirror after collimating the secondary . will the secondary mirros still remain well collimated…and when do you know what is needed to be collimated? or you always have to adjust both of them?

Giraldo Pino says:

What’s the name of that laser you used?

BlaggerDagger says:

what size is the allen key used? 2mm?

Squeakydizzle says:

What if I have not got a little black circle on my mirror to line the laser up against?

Panspermia Hunter says:

Great demo.
I think that primary mirror needs a wash 🙂

Taylor Cuadros says:

hi i have a celestron powerseeker 127eq and i don’t know anything about telescopes and i want to learn. I’m so facanated with the night sky but when i take it out i can never seem to be able to see the planets. I do have several eye pieces with different strengths . I can see the moon with little troubles. but im having a lot of problems like when i switch eye pieces i have to find the planet again and that’s no easy task.

Corky Cat says:

Do I need to loosen off the Philips screw on the secondary mirror before adjusting the hex screws on the secondary mirror? Had x2 SW scopes and the Hex screws were locked tight? Thanks John

Cabko2691 says:

Thank you guys i was worried about collimation, but im not anymore! Gonna buy the Newtonian i´ve been dreaming of 🙂 Greetings from Slovakia

MakoRuu says:

I just got a Celestron Powerseeker 114AZ.

I believe the collimation may be off. The images appear a little blurry and slightly askew.

Is there a technique to adjust it without using the laser? As I do not have one.

Dan Kahraman says:

Thank you very much guys!

zytigon says:

What about a safety warning about lasers at the start of your video ? See,”How to Collimate a Telescope – Orion Telescopes and Binoculars” on Youtube channel, “Orion Telescopes and Binoculars” . At 9:30 the lecturer says to point the telescope at a white wall first of all to make sure the mirrors are not so far off that the laser is exiting the tube; otherwise it could enter your eye & cause damage.

Well how far out would the spot need to be on the primary mirror to actually miss the secondary mirror and exit the tube ?

Rodier Ratafakus says:

Hi, I have 8 dobson.. as its on this video.. but I dont have that on bottom.. is it big problem?

washere961 says:

How would I center the laser on my telescope if I don’t have the ring in the center of the primary mirror

ohmymonkey22 says:

Ralph is cute. Now I will not worry so much about adjusting my scope. I have a nice size scope but plan on spending a bit more to see into deep space. I hope I can one day make one from scratch which would be awesome.i need to use my filters more so I can see colors better until I get a larger scope. Don’t mind cause the one I have is already heavy and large.

Mohammed Ali Aziz says:


Alan Willison says:

Actually, the first thing you should do is check that the laser beam is coming out of the collimator parallel to the collimator body. If it isn’t then you will make matters worse.

radioman970 says:

brave! having the tool ready to fall in there and give you a million years bad luck!

Solar Wind says:

Good instructions! Thanks much.

trumbettier says:

Thank you for explaining how to collimate the primary and secondary mirrors from an almost worst case scenario. Often people explaining things don’t realise even the simplest things can be a mystery to those who have never been anywhere near them. Now, thanks to you, I see how simple collimation is.

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