Collimation

[Joem]

How long does collimating a 6" dobsonian telescope take, is it difficult and are ther any specific tools I need??

[kniclander]

if it is f8 it is very easy because you don't need to be very accurate. you probably need an allan key (hex key) to adjust the secondary. you need either to buy a gadget (cheshire or laser) or for a cheap and cheerful approach just make a small (1-2mm) hole in the the middle of the little cap that came with your scope in the focusser (assuming it's a skywatcher or something similar) or apparently you can use a film cannister. Look for Astro_baby's collimation guide on here which i think lots of people on here probably learnt from.

good luck

[Tim]

There you have it. The answer to all parts of the question, is in fact, "yes and no".

For most visual requirements as with a dobsonian, you can get quite accurate collimation pretty easily. A great trick shown to me this year at Kelling Star Party (thanks Brian!) was to lay the telescope on a table or stool with the eyepiece holder pointing at an angle you can look down it when you take a few steps back from it.

When your collimation is good, you will be able to see your own iris reflected perfectly in the middle of the eyepiece holder.

It is worth spending a little extra time getting it as good as you can, as it especially helps when viewing planets and clusters.

As stated, look for Mels (astrobaby) guide on here, or google "Newtonian collimation", there are several step by step video guides to help you.

Probably the easiest tool to use is a laser, and the most accurate is a chesire. I use them in conjunction, and then finish off with the eyeball test

Good luck!

TJ

[Astro_Baby]

The link to my guide is Astro Babys Guide to Collimation

[Joem]

How often would you need to colimate a dob if you were to keep it in more or less the same posistion???

[markystars]

Probably worth checking regularly (once every 1-2 weeks) as it only takes seconds to check. Once checked you will no if it needs collimating, once collimated the first time, it shouldnt take much for minor adjustments in the future

Mark.

[Sunwind]

I havn't collimated my 10" dob since I got it a few weeks ago... it just seems really complicated and I don't have a collimating tool or anything I can use to do it with =(

[yeti monster]

You should be able to get is fairly close without resorting to any instruments. I followed Astrobabys guide, but not having a collimator, I estimated where the secondary was set and then adjusted the primary (with donut centred) to show as per the guide. Results were favourable, especially as the previous owner of the scope only sold it due to not being able to see anything through it............

I do plan to buy a cheshire at some point, but haven't really felt a huge need as yet (not getting enough clear nights whilst at home).

[TheThing]

In conjunction with AB's brilliant guide, I find this video very helpful.

In fact, the whole site is full of very useful video primers on a host of subjects.

[Astro_Baby]

The complexity is more apperant than real. Its very hard to explain collimation through teext and words (and even pictures) but is very easy to show someone on the spot as it were.

Its more fiddly than complicated.

[Tim]

Probably a laser is the easiest tool for collimating a dob. You can adjust the primary whilst watching in real time how it affects the alignment.

[Orion]

The complexity is more apperant than real. Its very hard to explain collimation through teext and words (and even pictures) but is very easy to show someone on the spot as it were.

Its more fiddly than complicated.

Bang on!

I was a bit concerned about how difficult it may be, and after taking advice on here I bought a cheshire, and followed Astro Babys guide.

I now have to confess, I must be sick, because I really enjoy collimating my scope. I would (and have) completely stripped down the telescope and rebuilt with no concerns at all.

As long as you have some common sense it should be a breeze after a couple of go's.

Get a cheshire and learn how to do it, then if you feel you need/want it, get a decent laser to nail the last bit out of the primary.

The main effort regarding collimation on a newt is getting the secondary correct.

[Astro_Baby]

All reflector owners enjoy collimation Anyway it gives you something to do when the clouds are around as well as making you look clever to friends and family

[PhoenixRising]

I do love a good collimation session...

Just as well, as my 150PL needs doing nearly every time as the focuser is slack

Only 6 weeks old too...

[TheThing]

I put it off for years initially, but when I finally neede to do it, it was much easier than I feared. To begin with, I had pretty good results just doing it by eye, but I now have a Cheshire for when I next need to collimate.