collimating my scope without extra tools?

[Sunwind]

I havn't collimated my scope since I got it a few months ago, but I didn't really think it was necessary since the views always seemed really clear and not blurry or anything.

but i've been reading about collimating and they all say you need some collimating tool (which I don't have) and something like a laser collimator.. all this stuff seems to cost a ton of money and for something I will hardly ever use aswell. is it possible to collimate my scope without any special tools? the manual that came with it claim it is possible but I can't understand the instructions they aren't very descriptive ;_:

any help?

and.. if my scope doesn't need collimating how will I know, will I not just end up possibly making it worse?

[yeti monster]

You can make a collimating cap. Using a suitable plastic cap to go over your focuser, with a 1.5-2mm hole bored dead centre. The idea is to have your eye looking directly down the centre of the focuser tube at the secondary mirror. Basically, follow Astro babys collimation gude, but without the cheshire or laser collimator. I did this when I got my Celestron 114, which was so far out that the PO gave up on trying to see the moon and was happy to sell it for 30 quid. Any how, the rough collimation worked well, and when I got a cheshire, I found it to be not very far out at all, and I hadn't made a collimation cap! Your Primary should have a centring "donut", which also has to be dead centre.

[brianb]

is it possible to collimate my scope without any special tools?

Those fancy devices only get you so close anyway, for final tweaks you need to use the view of a natural or artificial star at very high power in good steady seeing (or better).

Laser collimators are especially prone to misuse, they're often out of alignment themselves & (unless properly adjusted) so are just a convenient way of copying their error into your scope.

[phattanglo]

After reading the advice on SGL I think anyone on a tight budget will be happy with the results using a 35mm film canister with a central hole in the lid, then just a final tweak while observing an out of focus star.

[brianb]

just a final tweak while observing an out of focus star.

The final tweak is with the star in focus ... out of focus is much less sensitive though it does help you get near enough to make that final tweak.

[phattanglo]

Is the out of focus view the one that gives you concentric rings arount the central point if the scope is correctly collimated ?

[Astro_Baby]

Yes - if you take a look at my colimation guide on astro-baby.com you will see a pic of a collimation cap and also what defocused stars look like as well as the more common signs indicating problems.

You can do ok with a colli cap but I just find a Cheshire is simpler and not very expensive.

Depending on where and how you move your scope will decide how often it needs recollimating. Ignore the usual blurb that refelectors need lots of collimation. Mine hardly ever does even though its always transported by car to a site.

Much depends on factors like how carefully the scope is moved around, bumps and knocks but also whether the primary is secured well. New scopes seem to ofetn have overly loose primary mirror retaining clips whcih will mean collimation slips very easily.

[TopHouse]

When my 200p got home the locking screws for the primary were all loose.

[Doc]

Truss dobs often need collimating. Mine normally needs a tweak everytime I use it. A collicap is a cheap way to get pretty good collimation. You can then do the final tweaks on a star test.

Also I never use the locking nuts as I find this move the mirror slightlly when tightened.

[TopHouse]

Also I never use the locking nuts as I find this move the mirror slightlly when tightened.

Yep, I found that, so whilst watching the laser on the target on the laser collimater i backed off with the lockers, then tweaked the adjustments and retightened the lockers which then brought it back in. I think they call my disease COCD (Collimation Obsessive Compulsive Disorder)