What Collimation tool to buy

[Blackant (Ant)]

Hi all,

I've been lurking on this site for a while, reading threads and learning heaps. I've been gazing at the stars on and off since I was a kid, and I've had a lot of fun the last few years with a pair of 10 x 50 and 15 x 70 binoculars, a couple of star charts and some binocular astronomy books.

I'm getting pretty excited though, cause I've got the go ahead off my financial adviser and wife to buy an 8" GSO Dobsonian from Andrew's communications at tax time.

I need to get a collimation tool for it, and I wouldn't have a clue what to look for, or what would be best for an 8" Dobsonian.

Confession time now, it won't be my first telescope. I inherited a 114mm York Skyrover newtonian on an equatorial mount off my uncle many years ago, but to be honest, I never really got along with it. It 's been a bit of a relief to read a lot of the beginner threads on here to see that an equatorial mount isn't always the best way to go as a beginner. After reading up on how to collimate though, I'm beginning to think that this was half the problem with it, and while I wait for my 8" dob, I may as well pull this out and give it another go

Previously I've just used a film cannister with a hole cut in it, but I'm thinking there must be a reason there are all these tools around for collimation

So, what would be recomended as a collimation tool which would suit a 8" dob, and a 4.5" newtonian reflector?

Thanks all,

Kind regards

Ant

[multiweb (Marc)]

A laser collimator is handy to do a quick alignment but a cheshire is needed to do a precise alignment. I bought a kit from http://www.catseyecollimation.com/ a while back. Money well spent.

[Paddy (Patrick)]

I find that a laser collimator is sufficient as long as it is itself collimated, which is not difficult.

[torana68 (Roger)]

dont know there are any duds (but cheaper is rarely better) but I do like my laser one, and I can see that its better barlowed, so maybe if you think you will be around long enough to get the advantages v cost look for a barlowed laser , someone on here might be able to recommend one. (search the forums for colimation and read all the info , it will help you in your decision)
Roger

[Rick Petrie]

Hi Anthony and to IIS.
A good and reliable tool for the job would be a collimating cheshire eyepiece which you can obtain for about $89. I use the Orion brand and have found them to be the ideal reasonably priced and good quality tool for the job.
If you check the following link it will explain most or all that you would need to know to collimate a Dob.
It will take some time to master all the reflections that you see but persevere and you will eventually become competent at it.
Good luck and enjoy your scopes.
Cheers Rick
http://www.propermotion.com/jwreed/ATM/Collimate/Chesire.htm

[Paddy (Patrick)]

Originally Posted by torana68

dont know there are any duds (but cheaper is rarely better) but I do like my laser one, and I can see that its better barlowed, so maybe if you think you will be around long enough to get the advantages v cost look for a barlowed laser , someone on here might be able to recommend one. (search the forums for colimation and read all the info , it will help you in your decision)
Roger

I use an astro systems barlowed laser available from SDM telescopes for $198

http://www.sdmtelescopes.com.au/shop...1258f8a0d5c738

This works really well in a truss dob which enables an easy view of relfection of the barlow end in the secondary whilst fiddling with the primary adjustment screws. I haven't tried it in a tube reflector, but would imagine its a little trickier.

[astro_nutt]

Hi Anthony,
Congrats on getting a new scope..I'm sure you'll enjoy many years of viewing...as to collimation tools I use a cheshire crosshair to align the secondary under the focuser..(after ensuring the focuser has itself been squared against the tube and aligned)..then to align the secondary to the primary...generally the crosshairs on the chershire should align on top to the spider and the crosshairs should centre on the primay's collimation ring..after this I would use a laser to "fine tune" the collimation until the beam returns precisely to it's source...
Cheers!

[norm]

Hi Ant,

Check out this site if you haven't already:

http://www.andysshotglass.com/ and drill down until you find collimation.

My preference is the AstroSystems laser collimator - might appear pricey, but works a treat.

Once you have it sorted, collimation takes only a few mins - literally.

Clear Skies
Norm

[ausastronomer (John Bambury)]

Originally Posted by multiweb

A laser collimator is handy to do a quick alignment but a cheshire is needed to do a precise alignment. I bought a kit from http://www.catseyecollimation.com/ a while back. Money well spent.

This is the best information given so far in this thread.

A laser collimator on its own is not capable of properly collimating a telescope from scratch. It is only suitable for adjusting the primary and secondary mirror tilts. In other words touch ups on an "almost" collimated telescope. The laser is not capable of helping with the lateral positioning of the secondary mirror, or its rotation. Note, that once these adjustments are correct they rarely have to be adjusted again. The laser is handy once these adjustments are made and known to be correct. More importantly, with a laser collimator the secondary mirror and primary mirror tilts can be adjusted so as the telescope "appears" collimated, when in fact it is way out because the lateral positioning and or the rotation of the secondary mirror is out. Someone that is very experienced in collimating newtonians can "eyeball" the secondary and get it right, thus allowing them to get away with "just owning a laser". This isn't something for anyone that is not very experienced in collimation IMO.

Cheers,
John B

[Blackant (Ant)]

Wow, thanks everyone for the welcome, advice and the quick replies

Unfortunately money is going to probably be an factor, but having said that both the Cat's eye ones and the Orion Collimating eyepiece are both within my budget.

With the cat's eye cheshire kits, are these the one's people meant?

http://www.catseyecollimation.com/cekit1s.jpg

I did a fair bit of reading about what you can use before posting, but to be honest I was a bit bamboozled by all the information

This has helped a lot, ta.

Kind regards

Ant

[multiweb (Marc)]

Originally Posted by Blackant

Wow, thanks everyone for the welcome, advice and the quick replies

Unfortunately money is going to probably be an factor, but having said that both the Cat's eye ones and the Orion Collimating eyepiece are both within my budget.

With the cat's eye cheshire kits, are these the one's people meant?

http://www.catseyecollimation.com/cekit1s.jpg

I did a fair bit of reading about what you can use before posting, but to be honest I was a bit bamboozled by all the information

This has helped a lot, ta.

Kind regards

Ant

Ok, get a small laser collimator for the field (approx $150). Reason: when you're in the dark you want something quick and painless to "finish off" your collimation and you won't see any mirror central spot in the dark. The cheshire won't be practical.

At home in daylight it's a different story. You can make a sight tube (PVC pipe + fish line) with a reticule to center the secondary and buy a cheap cheshire (approx $50) to do the primary rough alignment. Later on invest in the CatEye tool kit. ($$)

If you ever get a very big aperture dobsonian a holographic laser collimator (approx. $300) is the way to go. It projects a grid and a central dot but you need to see the reflection into the secondary from the front of the tube so it needs to be pretty wide (might not work on your 8" DOB). For a big DOB that's the quickest way to align and collimate on the field. Literally 1 minute or so.

You also have to make sure your laser collimator is itself "collimated". If you stick it in a lathe or rotate it and project the dot on a wall at let's say 2-3m the dot should "reasonably" stay centered and not circle around. They rarely come aligned out of the box. Worth checking because then you'll really screw up your scope collimation if you use it and do more bad than good. Once your laser collimator is set put it in a safe place and don't drop it or it'll go out again.

Have fun.

[scumbag1010]

Not the same Blackant from EK

[bmitchell82 (Brendan)]

If you get one of the standard skywatcher cheshire collminators they have a 45deg cutout, you can shine your red light and do it in the dark of night if your worried about collmination and in anycase is actually better than using just daylight! it highlights the central spot and the cheshire spot...

My best advice to save your hair and pain, is go and get somebody to show you only suffer the pian of learning yourself when there is no other option.

With my standard Skywatcher cheshire i can obtain accurate collmination for 20min exposures for astrophotography! so im happy presently. and i made a laser collminator for ease of getting the secondary angle. but in anycase you can use a cheshire to do that once you know how.!

[GrahamL]

I've stuck with my $29 andrews chesire and find it meets my needs .

http://www.piscescs.com/astro/collimat/notools2.html

[Blackant (Ant)]

Hmmm I'll have to think about this one. I'd really like to spend less than $100 just to start with, so I'm thinking either the skywatcher cheshire or the orion collimating eyepiece. I have another rather expensive hobby which I've spent a lot of $$ on this year, so I don't want to push it too far, LOL.

The vast majority of the time I'll be observing from my backyard, so hopefully I won't have to collimate in the field much to start with and won't need a laser just yet. The plan is to collimate inside, very gently carry it the 10 metres from the spare room to out the back and set up.

I might even have a go at making one of these while I wait for it to arrive:

http://www.atmsite.org/contrib/Carli...kolli2.htm#DIY

has anyone had any luck with them before? I can imagine one small measurement off while making it equals one big collimation error when using it LOL

If I have any trouble I'll join the Astronomical Society of Tasmania again, I probably should anyway. I've been a member before over the years, and they are a lovely helpful group. Only prob is I live out in the country and I find I hardly ever get to meetings to make the membership worth while...

Thanks again for the advice,

Kind regards

Ant

Originally Posted by scumbag1010

Not the same Blackant from EK

Yep, thats me

Astronomy goes well with powerkiting I find As the days get short and the wind too light for kite jumping and landboarding after work, all my gear starts to come back out for astronomy

[Blackant (Ant)]

Originally Posted by nightstalker

I've stuck with my $29 andrews chesire and find it meets my needs .

http://www.piscescs.com/astro/collimat/notools2.html

$29 sounds good, great article too, ta

[TrevorW]

For a Newtonian for visual observation you can't go past collimation by eye

It works

Cheers

[Rick Petrie]

Originally Posted by TrevorW

For a Newtonian for visual observation you can't go past collimation by eye

It works

Cheers

It probably works to a degree for an experienced observer like yourself, but for a beginner wanting to see all that they should, some sort of tool other than eye would be necessary to correctly collimate their scope and learning is part of the fun. We don't want new people to the hobby losing interest due to poor images when they could have nice crisp ones.

[ausastronomer (John Bambury)]

Originally Posted by TrevorW

For a Newtonian for visual observation you can't go past collimation by eye

It works

Cheers

That is without question the "worst" advice given so far in this thread IMO.

You can do it, I can do it and their are dozens of other people that can do it. All those that can do it have been collimating newtonians for years. It isn't the way to go for someone that is inexperienced in collimation IMO. Moreso, it isn't the way to go for someone that has just asked, "what collimation tool should I buy?"

Cheers,
John B

[erick (Eric)]

Ant, whatever tool you end up with, it would be best if it were a snug fit into the focusser. I had a GSO laser and still have one of the el-cheapo (like $29 or whatever - someone threw it at me in disgust!) cheshires, both with 1.25" barrels. I was shown a trick which I have used successfully on both. I wrapped one layer of contact (yes, what we put down in the kitchen drawers!) around the barrel and both became a snug fit in the GSO 2"-->1.25" reducer. Both did a good job (sufficient for me) after that.

http://www.iceinspace.com.au/forum/s...ad.php?t=28643

I have graduated to a Hotech self-centring laser collimator, but still happily use my cheap, contact wrapped, Cheshire from time to time.