OK so I went to pick up the telescope and binoculars today. I have never really used the scope, it's a 4.5" Tasco Newtonian (yeah, I know, but whatever, it's gotta work for now)

Anyway, how do I collimate the darned thing without a laser collimating eyepiece?

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You may want to get a book, or failing that, find a website that describes the process.

I used to use a plastic 35mm film canister, with a pin hole in the lid and the bottom cut out. Of course, this requires you to actually find such a thing lying around, and since most people no longer use film...

Anyway, the film container fits in the focuser, you look through the pinhole, and you can use that to line up the secondary mirror.

But a book or website that gives the steps is what you really need.

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Here are some websites that explain the procedure involved in collimating a Newtonian telescope:

http://www.amateurastronomy.com/collimate.html

http://www.atmsite.org/contrib/Carlin/collimation/

http://www.oarval.org/collimatE.htm

http://www.catseyecollimation.com/mccluney.html

http://www.cloudynights.com/documents/primer.pdf

http://web.telia.com/~u41105032/myths/myths.htm

By the way, a laser collimator is not an eyepiece and is not absolutely required to perform collimation. You may be thinking of a Cheshire eyepiece.

Dave Mitsky

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Collimating at f/8 is very non critical compared to f/4, A simple site tube as Aurora details is about as precise as you need be. Heck at f/8 I often just eyeball it by centering my eye as well as possible in the draw tube at the image plane. You have lots of leeway at f/8 without it botherng the image much at all. For my f/5 I do use Orion's combination cross hair sight tube (I wish it was double cross hair)/Cheshire "eyepiece". The Cheshire part is helpful for collimating at night as you can use your map light to illuminate what you are doing by shining it onto the 45 degree matte face. I then finish up with star alignment for the final tweak of the f/5. I've never found a star alignment needed with the f/8, it was already close enough.

As explained in the last link Dave gives, and maybe others I've not looked, the laser collimator isn't nearly as useful as many think and can, in fact, lead to a really lousy collimation job. I've seen it happen many times. It's a great way to go wrong with confidence! Correctly done, a barlowed laser is more useful but totally unneeded at f/8 as far as I'm concerned. A simple site tube like Aurora details does the job just fine. Especially if you only need to align in daylight.

Rick

From his other post though, it sounds as though it is an f/4, not an f/8.

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I hadn't caught that. All 4.5" Tasco's I saw at Hyde were spherical mirror f/8 or slower reflectors. Guess I assumed that's what it was. An f/4 4.5" is a rather odd combination! At f/4 he'll want a Cheshire for more accurate collimation.

Rick

Not really. The Orion StarBlasts are very popular f/4 reflectors. It also seems to be that the 4.5'' f/4 Tascos were the best scopes the company produced in recent years.

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