Collimation

[milkyjoe]

Hi folks,

Sorry if this topic has been covered on here a million times before, but I have a query.

I was outside last night with my 3.5" mak cass under very clear (but very cold) conditions, attempting to observe mars in the east at around 11.30pm. After setting up my scope, I popped in my meade 3000 16mm ep, looked and all I could see was an small unstable orange blob! I appreciate my scope is small and I know I'm not going to see much detail (if anything at all), but mars did not look very clear to me; I have observed jupiter with more crispness and clarity than this so I am wondering if my scope needs collimating!?!

If it does need collimating, what is the best way to test for this and how do I go about doing it, without damaging the mirror!?

I look forward to some replies on this subject.

Many thanks,

Rick.

[Cornelius Varley]

It is more likely to be the atmospheric conditions than the collimation. You can easily check if the collimation is out by aiming the telescope at a medium may star and defocus the telescope, use a highish power eyepiece for this. If the telescope is in collimation you should see a series of concentric rings. If they are not concentric the telescope is out of collimation. Make keep their collimation well so I doubt the collimation is a problem.

Peter

[Mr Spock]

With that size of scope all you are likely to see at the moment is a small orange blob.

[milkyjoe]

Thanks for your advice Peter, but what is a 'medium may star?' I am fairly new to astronomy and still learning the constellations.

Also, is mars a small orange blob?

Thanks,

Rick.

[milkyjoe]

You beat me to it Mr Spock! lol

[Cornelius Varley]

Thanks for your advice Peter, but what is a 'medium may star?' I am fairly new to astronomy and still learning the constellations.

Also, is mars a small orange blob?

Thanks,

Rick.

Somehow medium mag became medium may. Must be the chell specker

Peter

[umadog]

A misscollimated telescope produces a blurry image, not an unstable image. For an image to be unstable, something must be moving. Your mirrors are still. So what's moving is the air; specifically, light being refracted through warmer and colder regions of turbulent air.

There are two sources of this. Firstly, the atmosphere. If Mars is fairly low in the sky or the sky is turbulent, then the image won't look good. Secondly, you say that you set up the scope then looked through it right away. Maks and SCTs need to be cooled down to ambient temperature otherwise they produce very unstable images. Out of all telescope designs, Maks and SCTs with closed tubes need the most cool-down time.