Science & Mathematics » Astronomy & Space » Could you help me with collimating my Newtownian telescope?

Could you help me with collimating my Newtownian telescope?

I have a Newtonian reflector telescope that I'm practically scared to use, partly because I can't find a good, "Collimation For Idiots," comprehendable website and partly because nobody I know knows what the heck I'm talking about. Any tips, tricks, or recommended websites out there?

That pages seems like it would be really useful. Good luck - if it doesn't work, try contacting a local astronomy club and asking for more help.

Once you do it the first time, you'll think it's one of the easiest things in the world.

The main thing that will make it simple is to put a dot in the center of the mirror. I use black plastic electrical tape, and cut out a small dot. You could also go buy black round stickers at an office supply store. Use a cloth tape measure to get the thing as close to the center of the mirror as you can. If it is off by a small fraction of an inch -- that won't matter too much in the end.

I am going to look for the website that had the set of procedures I use (printed out, and never saved the link). I'll come back and edit, with the link. Stand by.
EDIT: That site is no longer there.

If you put the small dot on the center of your mirror, things will be much clearer for what to adjust in collimation.

The only other thing I bought, was an eyepiece with no lens, and a small (4 mm) hole centered on the eyepiece. That helped, also.

Once you get your diagonal mirror locked in, you shouldn't have to mess with it (at least I don't on my scope). Then it's just a matter of keeping the main mirror aligned in its cell. I am now in the habit of adjusting my main mirror whenever I take the 'scope out.



if you take the eyepiece out and look through the hole in a perfectly collimated scope you should be able to see the reflection of your eye in the center of the main mirror along with the ummm..... thingies that hold the secondary mirror in place.

your eye should be in the center of the main mirror. adjust the set screws on the main mirror to try to line your eye up with the center, if those screws won't do it then try the screws at the back of the secondary mirror. you have to be patient and calm i know my own scope needs to be collimated. i thought it was ok until i tried to look at saturn and it looked more like a comet, lol. now when i look through the eyepiece hole i wonder how i ever thought it was lined up right.

i hope this helps and doesn't confuse you more, if all else fails take it to a pro or get a tool for it.

Start by taking the eyepiece out. Look in where the eyepiece is normally, and you will see the secondary mirror (this is the little flat mirror held in the center of the tube by the "spider").

STEP 1: the secondary should be centered in your field of view. If it isn't, adjust the spider (which holds the secondary) so that it is centered.
STEP 2: you should be able to see the primary mirror reflected in the secondary, and the image of the primary should be centered. If it's not centered, adjust the TILT of the secondary (not the position) so that it is centered.
STEP 3: Looking at the image of the primary, you should be able to see the image of the outer end of the tube centered in the primary. If the tube isn't centered, adjust the tilt of the primary until it is centered.

And that's all you need to do, unless your really really finnicky.

There are many resources on the web about this - just search for "Newtonian collimation". They say basically the same thing, just different wording, so you may prefer one over the other. Since this depends on your style, I won't give any specific web resource; you may try this one:
You may join a telescope-related newsgroup; in the Resources section, you are likely to find one or more collimating-related file.

Collimating can be done in several ways:
1. Without tools (looking through the center of the focuser tube, eventually using a peephole, to help you get the tube cneter)
2. Using simple conventionsl tools, such as a Cheshire eyepiece)
3. Using a laser collimator, probably the most expensive tool (50 to 80 USD, range is approximate), and some say that it is the most precise. Laser collimators usually come with instructions.
4. A simpler method is the barlowed laser collimation (search for "barlowed laser"); for this, you can improvise the tool with a laser pointer, and instead of a barlow, use one of the diffraction patterns supplied with the pointer; unlike the laser collimator, it does not need to be precisely aligned, it only needs to start in the center of the focuser tube.