how to colliminate my astromaster 130

[johnkirkpatrick]

Just a quick question for you all,

How do I know when my astromaster 130 needs to be collimanated and how do i do it without any tools?

(Please forgive my spelling )

[John]

Next clear night, find a star (Polaris is good as it does not move) then put it in focus with your 10mm eyepiece then slowly put it out of focus so it expands into a small disk with a dark "hole" in the centre (bit like a polo mint). If the dark hole is right in the centre of the out of focus star then you collimation is OK. If it's offset to one side or other then collimation adjustments are needed.

You will need to make something to centre your eye in the drawtube when collimating the scope - often people use an old 35mm film cannister with a 2mm hole bored right in the centre to peep though.

Have a look at Astro Baby's collimation guide for help on the collimation process:

Astro Babys Guide to Collimation

[johnkirkpatrick]

cheers mate, I know what you mean. i had that when looking at mars the other night when getting it in focus, so i thing im ok now. but now i know how and when to do it.

[LukeSkywatcher]

If you feel the collimation is OK with the scope then dont change it. If you think it is off then a simple collimation cap as John says will do the trick. Once you look through the hole in the cap and you can see the whole primary mirror with the seconday centred and the donut centered in the secondary and your eyeball in the donut.............you are good to go.

A scope of 130mm apeture really should not need collimating very often unless you transport it over major potholes for miles and miles and even then it should still hold. Its only when you go above 130mm that it may need doing often. But i guess a quick check before every use is no harm.

(my comments are not my own.....just what i have learned online about collimation).

Next clear night, find a star (Polaris is good as it does not move) then put it in focus with your 10mm eyepiece then slowly put it out of focus so it expands into a small disk with a dark "hole" in the centre (bit like a polo mint). If the dark hole is right in the centre of the out of focus star then you collimation is OK.

Is that dark "hole" the secondary mirror or the donut on the primary? The fact its a hole makes me thing it is the donut. Mine is pretty much very well centred so i guess i am good to go.

A laser collimator will make your collimation 100% spot on. BUT a simple home made collimation cap will get you there about 95% (so i read). 95% works for me.

I'm such a skinflint.

P.S.~~~my 130mm scope was off by quite a bit when it atrrived but i found out the reason was because the spider arm holding the secondary mirror was loose and rotated a bit. I just tightened it and things were fine. I still did a full collimation though.

[Astro_Baby]

I'd sugget not using a laser in a small scope. The focusers are arely stable enough to give reliable results and cheap lasers often cause more problems than they solve.

If you want a good collimation solution a Cheshire is the way to go. It will collimate any reflector very well, they are simple and cheap and well worth investing in for collimation.

Mel

ps dont get obsessed with collimation.

[TopHouse]

ps dont get obsessed with collimation.

Yesss, join my collimater OCD support group

[LukeSkywatcher]

ps dont get obsessed with collimation.

Totally agree. It is NOT the be all and end all of everything. Your scope will work ok without it.

Its a good lesson to learn by doing it though. Do it once and you are set for life (knowing how to do it).

Until you do it..............it really does seem like the scariest thing on the face of the earth. It really is NOT that big of a deal.

I prefer to call it "aligning the telescope mirrors" because that is what it is. Collimation sounds very technical and scarey.

[John]

...Is that dark "hole" the secondary mirror or the donut on the primary? The fact its a hole makes me thing it is the donut. Mine is pretty much very well centred so i guess i am good to go...

It's more of a dark shadow really and it's the silhouette of the secondary mirror.

I don't recommend a doughnut, or indeed any form of cake, on the primary - the jam and crumbs are hard to shift

[LukeSkywatcher]

It's more of a dark shadow really and it's the silhouette of the secondary mirror.

I don't recommend a doughnut, or indeed any form of cake, on the primary - the jam and crumbs are hard to shift

Just as i thought. Its the secondary silhouette. I dont have a sweet tooth so the only thing that may hit my primary is a bit of cheese or pickle.