More confused then ever

[stopusinmyid (Tammy)]

Hi all,
I have been looking at getting a laser collimator, think my Astromaster needs it. Well I rang Andrews today to purchase one but they are out of stock, won't be getting any in for a few weeks. So i decided to see what was available on the world wide web. Wellllll all that did was confuse me and made my brain tired from trying to understand it all.
There is so many to chose from. Someone put a post up on here 28/7/2008 asking about laser collimators. This is where the brain got saw, some say the laser collimator can be un-accurate due to needing adjustment itself. Some say the cheshire is good or the barlowed collimator is great or that they use two types to get the job done. All I am after is something user freindly without costing an arm and a leg (the tax return is almost gone ). So any suggestions appreciated,

[barx1963 (Malcolm)]

Hi Tammy
A 130mm scope doesn't need a great deal of fussing with collimation, I have one and have simply followed the instructions that came with it and then used the laser and found absolutely no difference in the image.
Of course mine was a longer focal length at 900mm while yours is 650mm? Shorter focal length makes collimation more critical but I would be surprised if it made a huge difference.
If your scope came with instructions follow these, one you have done it a couple of times you will find it easier.

Malcolm

[stopusinmyid (Tammy)]

A 130mm scope doesn't need a great deal of fussing with collimation,

Malcolm

Cheers for that. I'll have a proper look at the instructions (again) , but I am currently waiting for my 10" dob to arrive (that's where a chunk of tax return has gone) and I'm guessing I'll need to check this one a bit more often. Have plans to let brother in law borrow the Astromaster and just want to make sure it's all aligned.

[barx1963 (Malcolm)]

Yes once we get to 10" you need to take a bit more care with collimation, but a laser isn't necessarily the easy fix, really a laser is the last step in the collimation process.
Here is the guide I used to learn the basics
http://www.astro-baby.com/collimatio...on%20guide.htm
Hope it helps

Malcolm

[Waxing_Gibbous (Peter)]

Don't be intimidated.
I needed a large beverage and a lie-down before I attempted my first collimation on a 12" GSO dob.
Using an Orion Laser jobbie it was done in under a minute!
Can't recommend them (lasers) highly enough.
'Howie Glatter' collimaters are supposed to be the business. Accurate to a 'T' and very well made. They are however around $200.
Learning the theory and basics of collimation is only a good thing, but using a laser will help you eliminate any eye-induced errors.
Plus they drive cats nuts which is always fun!
As a BTW - make sure everything is snugged-down tight before you start - focuser, EP holder, mount - otherwise you are likely to introduce flexure into the optical train and your collimation will be out.
G'Luck!
Peter

[stopusinmyid (Tammy)]

Thanks for all the advice. Still a little confused , but we will work it out. If we have too much trouble will just have to try and swindle a visit to Ian Musgraves place , get him to show us.

[astro_nutt]

Hi Tammy.
I first started learning collimation by using a cheshire crosshair. This will show you the position of the focuser to secondary mirror, then the seconday mirror to primary mirror. This means that when you look down the cheshire crosshair you will see the secondary mirror fitting exactly under it, and the reflection of the primary mirror within the secondary mirror. In the middle of the primary mirror you will see the centre spot and the cheshire crosshair should be in the middle of the centre spot. If the secondary mirror is held by a four-vane spider, you should be able to see the cheshire crosshair match up exactly with the four-vane spider. Once you have this alignment set up, you will only need a laser to fine tune it when required.
Cheers!

[stopusinmyid (Tammy)]

Cheers for that astro . That sounds easy enough to get us heading in the right direction. I compared my view through the focuser of our 130EQ to what the book was showing me and he looks spot on. When I looked through the focuser of the 10" the little circle I saw seemed to be on one of the lines but a little off on the other one, so am I right in guessing that it's out?

[astro_nutt]

Hi Tammy.
Sounds like the primary mirror needs adjustment, but only slightly. This is where your patience will be rewarded. Just remember which way you turned the adjustment knobs and by how much. After you have finished, please turn the locking screws until you feel resistance. No more force is needed as it may twist the mirror cell. I hope this helps.
Cheers!

[Matthew Lovell]

Confirm Collimation by Star Testing.