Hello Peter,
The Astro Baby method of collimation is and excellent one that Martin has posted
Follow Astro Baby's method and the secondary mirror will be properly aligned.
Please note a couple of things:
1, You need to deal with the secondary mirror first! Ignore this, and nothing you do will give you properly collimated optics. A Cheshire eyepiece is the tool for sorting out the secondary mirror, including making sure it is square with the focuser.
2,
A laser will not do anything for the secondary. A laser is used ONLY to do minute tweak to the secondary to centre the beam in the centre spot of the primary, after you've properly dealt with the secondary. Only then do you adjust the primary mirror.
I too thought I could collimate my Newt/dob exclusively with a laser. I started out collimating just with a Cheshire. A Cheshire will collimate both the secondary and primary mirrors. But a Cheshire is not the easiest tool to use with the primary. So I ditched it for a laser...
which I thought would do it all. I bought the laser from an astro retailer too. Problem is that even though astro retailers are well meaning and want to sell you the right tool for the job, they cannot know how competent you are at collimating Newts. So if you ask for a laser, they will sell you a laser, expecting that you know what you are doing. It is not their place to necessarily ask if you know or not... That's the way it is.
So, I started using my laser, and over the next few months instead of the image in my scope improving, it was getting worse and worse! Not only very frustrating, but very flaming annoying as I thought I was doing everything right.
Then, one night, out of sheer exasperation after trying everything I could think of, I looked down the draw tube of the focuser, and to my utmost surprise I saw the secondary mirror was so far out of position it was staggering! The secondary was not square with the, tilted out of position (due to the collimation screws), and not centred with the draw tube by a long margin!!! And this was all so obvious just by eyeballing down the draw tube.
It was only then that I realized that the laser will not deal with the secondary mirror as I thought it would. ONLY a Cheshire eyepiece will deal with the secondary mirror, and only after you've dealt with the secondary do you give the primary mirror any consideration.
And since that most eventful night, I have never had collimation issues. None that could not be traced back to some cock-up of mine...
You need at least a Cheshire to properly collimate your Newt - it will deal with both the secondary mirror and primary. A laser will help, but ONLY for the primary mirror, AND ONLY after you've used the Cheshire to sort out the secondary mirror first.
Alex.