How to collimate my 6" reflecting telescope?

Question

I understand I can collimate using a star

Answer 1

I assume you are talking about a Newtonian telescope. If so, then the collimation is fairly straightforward and not too critical, since you have only one curved optical element, the primary mirror. The secondary is flat.

First make sure that the secondary mirror is approximately in the right place---centered in the tube.

Make sure that the two angles of the secondary is about right. If you take out the eyepiece, and look straight down the eyepiece tube from a few feet away, you should see the center of the primary mirror.

Then all you need to do is make sure that a ray that comes in parallel to the axis of the tube and hits the primary mirror gets reflected back to the center of the eyepiece tube. This is a two-axis angle adjustment of the primary. It can be done in a crude way using the moon, or a streetlight or even a flashlight. (Of course you know not to look at the Sun.) Make sure the light from the object is shining straight down the telescope tube. You may be able to position the tube toward the source by looking at the shadow of the tube. Looking into the eyepiece holder, you should be able to see the light from the object. If not, you are badly out of alignment, and need to do a crude adjustment of the primary mirror angle so that the light can be seen.

At this point, you will be roughly aligned, and may find that the images are OK (free of coma) if you put in an eyepiece and focus. To achieve a better alignment, you will need to use a smaller light source, such as a bright star. The same procedure can be used, but the difficulty is making sure the light from the star is aligned with the telescope tube. If your finder scope is aligned and your clock drive is working, this may be straightforward. Simply adjust the angle of the primary mirror so that the star is centered in the eyepiece, while the tube is pointed precisely at the star, refocussing the eyepiece as necessary.

Answer 2

If you want really precise collimation, so that stars snap into sharp focus, it is a little more complex in practice than some of these answers suggest. And you will need collimation tools to do it well.

Here is a link to a short treatis on collimation that explains everything very thoroughly: http://www.catseyecollimation.com/mccluney.html

I am not affiliated with the maker of the Catseye collimation tools described on this site, but I do own them and highly recommend them. I use them to collimate my 18" reflector.

Answer 3

You can do it in the house during the day. Take the eyepiece out and look at the mirror through the drawtube. You should see the reflection of your eye, the diagonal and the front end of the tube all concentric with each other. If not, adjust the main mirror using the 3 screws on the back until it is. That is for a Newtonian reflector. For a Cassegrain, you adjust the secondary.

Answer 4

hi. once you get into your automobile the 1st element you do is alter the replicate so as which you spot wisely out the rear window. this could be a reasonably uncomplicated "collimation". In a reflecting 'scope there are 2 mirrors to alter. the common on the backside of the tube and the secondary on the eyepiece. start up by utilising adjusting the secondary until you spot the mirrored photograph of the common popular. The help struts might or won't be completely even, so forget approximately approximately them. as quickly as you get this an prolonged way put in a lens. Low means (intense style of mm, say 20 to 30) and seem at a megastar. In concentration it would be a tiny element yet will in all probability appear as if a small comet. on the common end of the 'scope there ought to be 3 screws that substitute the lean of the replicate. turn one in all them on a similar time as gazing the great call (a sturdy chum is effective). attempt to flow the screw that makes the top of the comet flow in the direction of the tail. somewhat difficult to describe yet you will see what I recommend. the item is to reproduction this until the great call is an exceptional a element as a probability remembering that no 'scope is appropriate. have enjoyable and robust success!