Collimation

 The drawback to a Newtonian telescope is that you have to align the mirrors. So how do you do that?

There are some ways to accomplish this. You can use a laser collimator or a  Cheshire eyepiece. 

The laser collimator shines a laser into where you put the eye piece. The laser then hits the secondary and then the primary and then returns the same way.

The Cheshire is basically crosshairs you sight down and line up the mirrors.

Both methods work. But I decided on the laser device. To be exact the Svbony model. So when you use a laser the laser needs to be lined up and down the center of the eyepiece holder. You would think that that is a simple thing right. No the laser collimator also needs to be collimated.

This laser is in a 1.25 inch form but comes with a 2 inch adapter if you can only use that. In the picture above you can see the target that the laser needs to hit in order for the mirrors to align.

I decided that two times the focal length which is about 60 inches would be my target distance for the laser to see how far off it was.  So I built a quick and dirty jig to hold the collimator. Just a small wood board with nails at 45 degrees to hold it. It does not need to hold it straight as all you care about is if the laser makes a tight circle ideally it does not move. You check this by making 1/4 turns and then marking a piece of paper where the laser hits. If you are OCD it is just the same spot. If you are not OCD maybe you allow it to vary a bit. But 10mm circle was a bit more then I wanted.

If you are wondering what is the deal with the blue tape? Well when they make the collimator they want it to fit in the 1.25 inch hole but not super tight. So when in the telescope it is loose and when you tighten the screws to make it more snug it is now slightly off center. A trick is to wrap blue painters tape around it and overlap it a bit. Then you run a razor knife down it to cut thru both layers. Remove the loose end then take apart the over lap and remove the piece underneath and place it back down with no overlap at all. It is a neat trick to make sure that all you do is increase the width without having any overlap. Now it is a snug fit it is perfectly centered.

When I checked how centered it was out of the box it was 10mm off. So I had to dig out the stuff they seal the adjustment screws with.

So once that was out it took me some time to actually get it centered. I was not keeping track of what I was doing too well plus I had to figure out that if you move one hex screw out you need to move one hex screw in. After resetting a few times I finally started just doing 1/8 turns out on one and 1/8 turns in on another. Eventually it just about dead on. Good enough for this guy.

I then went and collimated the scope by first aligning the secondary mirror once that was done then I aligned the primary. After struggling with the collimator doing the telescope was simple.

Now I wait for clear night sky's. Which have been gone since I collimated the telescope. Isn't that how it always is.