Dark art of collimation

[metz]

No wonder us newbies in the know stay away from reflectors not once ave i understood a thread on collimation ?? its like its a magic receipe passed down by a secret wizard sect ..eye of frog ..tail of newt...legs of spider etc then you think MMmmmm id like to own a nice dob 250 , then you read someones prize dob needs collimation coz a common house fly has bumped into it !! ok then you google collimation made easy only to find its made harder ?? wrote by another secret sect ? oh man !! ;)

[jnc71106]

I know what you mean. I took the plunge the other day and had a crack at collimating my newt for the first time.

Took a little while but I got there in the end.

Now I have done it once the next time should be easier. I hope

[peter shah]

no secrets....just practice.......

start from the focuser then to the secondary then to the primary....easy! YEAH RIGHT!

but it will teach you a lot about your scope

[NGC 1502]

Yes it can get confusing, especially if a war starts between "experts" with different methods

But it's not that bad really. I think it does help if you are a

DIY sort, as you will be more familiar with handling basic tools.

Some will say collimation needs to be done with each observing

session, but I've not found that, as long as the scope has not

been bumped around.

Good luck ! Ed.

[Parus major]

I read a bit on it before I got mine and it was all Greek to me. The secret recipe is actually having a Newt in front of you so you can see what is meant.

[kniclander]

No wonder us newbies in the know stay away from reflectors not once ave i understood a thread on collimation ?? its like its a magic receipe passed down by a secret wizard sect ..eye of frog ..tail of newt...legs of spider etc then you think MMmmmm id like to own a nice dob 200 , then you read someones prize dob needs collimation coz a common house fly has bumped into it !! ok then you google collimation made easy only to find its made harder ?? wrote by another secret sect ? oh man !!

what utter nonsense!

buy a newt. give it a go. check out "Andy's shot glass" - it's maybe not as thorough as some of the other guides but it's much simpler.

[sbooder]

Dob's usually have a long focal length so you can get away with a basic collimation to start with.

Just start with an old 35mm film canister and poke a hole in the convenient nipple in the centre of the lid, cut the bottom of the canister off and you have a collimation tool that fits your 1.25" focuser.

Start by making sure the secondary mirror surface is centred in the focuser and then make sure you can see all the primary mirror clips in the secondary by using the 3 screws at the opening of the scope on the secondary spider.

Then twiddle the 3 thumb screws at the bottom of your scope until the centre doughnut stuck on the primary surface is in the centre of the secondary view.

All this you do while looking through the little hole you pocked in your 35mm film canister (the small hole means your eye is viewing from the centre of the focuser).

Once you are accustomed to collimating in this way, buy yourself a Cheshire Collimator, still the best tool for collimating ever (unless you are collimating at night of course).

[starstalker]

what utter nonsense! From reading your post, I'm not at all surprised that you "ave" not once understood a thread on collimation.

buy a newt. give it a go. check out "Andy's shot glass" - it's maybe not as thorough as some of the other guides but it's much simpler.

thats a bit harsh!

[kniclander]

harsh but fair, no?

[sbooder]

harsh but fair, no?

No not really. The guy was just to make light of his lack of knowledge, to shoot anyone down like that for not knowing about collimation is hardly the way to encourage anyone.

[starstalker]

not really, we was all newbies once and the OP is obviously just using humour to ask for help and as for the "ave" jibe, this is just a forum not a spelling test,maybe just lighten up a bit

[kniclander]

not really, we was all newbies once and the OP is obviously just using humour to ask for help and as for the "ave" jibe, this is just a forum not a spelling test,maybe just lighten up a bit

ok, ok, i took the jibe out but the OP wasn't actually asking for help at all if you read his post - it was just a general rant against newts which the OP clearly knows nothing about - another newbie cd read it and be unnecessarily put off - that's what annoyed me.

[starstalker]

i see where you are coming from as well but theres a way of saying things,no worries mate forgive and forget! andy shotglass is a pretty good guide tho!

[kniclander]

i see where you are coming from as well but theres a way of saying things,no worries mate forgive and forget! andy shotglass is a pretty good guide tho!

(does that mean I can put the "jibe" back in....?)

[metz]

ok, ok, i took the jibe out but the OP wasn't actually asking for help at all if you read his post - it was just a general rant against newts which the OP clearly knows nothing about - another newbie cd read it and be unnecessarily put off - that's what annoyed me.

Oi captain charisma take a chill pill lighten up lol laughing out loud that means:)

[kniclander]

what is it you mean by this word l-a-u-g-h-i-n-g ?

sorry for being harsh (but fair)

captain charisma:)

[metz]

what is it you mean by this word l-a-u-g-h-i-n-g ?

sorry for being harsh (but fair)

captain charisma:)

thanks mate water off ducks back , nah worrys

[ronin]

eye of frog ..tail of newt...legs of spider

That's the problem, no bats wings.

Only way to find out is to give it a try. Some find it easy some don't. Some like a laser collimator some prefer a Cheshire. Cat's Eye collimators are so expensive that if you can afford one then pay someone else to do it instead.

Hell if you can collimate sufficently accurately with a film canister then use it, just so long as it works for you who cares.

On CN one of the uses described for a 4mm eyepiece was to push out the glass and use it to collimate a newtonian.

[Jason D]

Collimation is 50% knowledge and 50% tools.

Below is cut & paste of one of my posts on CN:

Based on my experience over the past few years helping others with collimation problems, here is a summary of what many of the new Newtonian reflector users had struggle with:

1- Facing collimation fear. The secondary mirror structure has 4 spider vanes thumb knobs, 1 central bolt, and 3 set screws. The focuser has 3 alignment set screws. The primary mirror has 3 collimation knobs and 3 locking screws. Too many knobs and too many screws to deal with. The only way to conquer collimation fear is knowledge and practice, practice, and more practice. It is like learning how to drive. Knowledge is important but nothing can replace learning driving behind the wheel – not even simulators. The same goes for collimation.

2- Dealing with mechanical frustration especially with the secondary mirror. It takes practice and potentially some mechanical modification to control the secondary mirror.

3- Not understanding the theory of collimation and the importance of different alignments. In a different forum, someone went out of his way to square the focuser and use a camera to center the secondary mirror under the focuser with high precision. But the same person did not pay as much attention to the primary mirror focal plane shift/tilt alignments. It is important to under the collimation theory at high-level to concentrate on the important alignments.

4- Not understanding how to use collimation tools. Again, in a different forum someone was getting frustrated because his laser did not agree with his collimation cap. It turns out that after collimating his scope with the laser, he used the collimation cap to assess the secondary position under the focuser. He did not know that a typical unbarlowed laser is not the proper tool nor it is intended to optimally position the secondary mirror under the focuser. That is the job for the sight-tube or holographic laser. In addition, he was not using the collimation cap properly since he used it to assess the secondary position rather than the primary alignment.

5- Not owning the proper set. There are 3 collimation alignments that we need tools for: Positioning the secondary optimally under the focuser, eliminating focal tilt errors, and eliminating focal shift errors. Each of the 3 alignments need a specialize tool. Some of the combo tools can handle several of these alignments. Some own several collimation tools targeting the same alignment without owning tools for the remaining alignments.

6- Not knowing how to perform star collimation correctly. Many defocus the star too much and end up attempting to correct the secondary offset as opposed to the primary alignment.

7- Relying on and trusting incorrect manuals. For example, many scope manuals show simplified diagrams of collimation where all circles are shown concentric. The off-center secondary mirror silhouette tends to confuse and frustrate new Newtonian owners.

Jason

[Jason D]

Cat's Eye collimators are so expensive that if you can afford one then pay someone else to do it instead.

But to be fair, a complete set of Catseye tools cost is comparable to a single premium eyepiece -- I am not even thinking of Ethos.

Jason

[Glen]

Practice practice practice, as said above hands on does help alot, but just understanding what it should/shouldnt look like takes a bit of 'out-side-the-box' thinking. example: Jason D's avatar

Edit: spelling and a note to say Jason D's avatar is what it should look like, if it looks like mine.. you have a problem.

[acey]

I think I used my 8-inch dob for about a year before I even heard of collimation, then I used the film cannister method and once I could see Jupiter's moons as discs I knew I was good enough.

Internet forums are a wonderful thing, but they do seem to have spread unneccessary fear among potential users of Newtonian telescopes. Just remember that this design has been productively used for hundreds of years, with excellent results - at a time when lasers were just a harmless twinkle in the eye of the inventor's great-great-grandmother.

As Isaac himself would surely tell you: it ain't rocket science!

[Astro_Baby]

You dont need a Catseye - a basic Cheshire will get good results.

I think a large part of the problem beginners have these days is they come in expecting it all to fall in their lap. They seem to expect telescopes to work like a DVD player when thay are hobbyist bits of gear.

Its a bit like buying a pair of skis and expecting to be able to immediately hit the slopes and ski like a champion.

Telescopes may not be as demanding as some hobbies but they still rquire a bit of effort from the user and a willingness to learn, read up, do research and most importantly PRACTICE.

You may have to collimate a refractor one day as well or even a real horror of a scope like a Rumak. Even if you dont collimate you will have to learn a dozen other things (at least). Thats part of the fun of the hobby or should be.

In many ways its down to the big hearted folk like Jason who puts a fair bash of time into helping the gormless newbies (like me once) who support this whole hobby.

ps - Eternally grateful to Jason there for helping me out sometime back and he is the real inspiration behind my own guide to collimation.

[Moonshane]

I bow to Jason's far greater knowledge than mine but I think too much is often made of collimation.

for me there are two kinds of collimation.

1) 'full collimation' if you have built your own scope and need to make the initial alignment of all the components.

2) 'maintenance' collimation (includes knocks and bumps as well as collimation before each session).

Unless you have bought a used scope and want to do a through check or have just made your own scope, I feel you can really ignore 1.

if you just want to ensure your scope will give good visual performance then 2 is all you need and this really only need take a couple of minutes before each session. this is all the vast majority of newt owners will ever need to do.

my maintenance method (with the scope usually at 45 degrees approx) is :

1. use a collimation cap to check the secondary is central in the focuser and that it is rounded - if not adjust with the placement of the centre screw and turning of the secondary - take care with this - various methods say why.

2. using the same tool, ensure that the whole of the primary and clips can be seen in the secondary and that it is as central as possible - if not, adjust with the secondary adjusters until it is. check stage 1. again and repeat as required. This adjustment is not often required but I always check it.

3. using my cheap and nasty free plastic Cheshire that came with the scope, I ensure the dot of the Cheshire is inside the doughnut on the primary (I do this at night usually with my red torch) - if not (and it's usually not, esp in the 12") adjust with the three primary adjusters until it is.

every now and again I use a 'proper' Cheshire to check a little more closely.

I am sure there are errors in the above method but it works for me and gives excellent views of the night sky, splits on tight doubles and great planetary and lunar detail at high mags. I have never got round to star testing properly mainly as the seeing is usually too bad to do it effectively!

Astro-baby's guide is great as is the one already mentioned.

Good luck.

[Pete Presland]

nobody has mentioned a laser collimator yet frowned upon by many,but they certainly work if your not sure using a cheshire