Permanent marker to centre spot primary mirror?

[EzyStyles]

Hi Guys,

My new GSO scope isn't centre spotted and was wondering if i can use a permanent marker just a small black dot rather than the white reinforcement rings as the surface area is smaller from a marker?

thanks.

[leon]

Eric i did mine last week, yea it will be fine, aparently it lasts a long time

[Starkler]

The white ring is the best if the size accurately matches the diameter of the bright ring image from the cheshire.

[EzyStyles]

thanks for the advice guys. Will do both :P

[davidpretorius]

I have a texta mark and it gets lost near the centre. A white ring would have been better.

[EzyStyles]

thanks davo. i get shakey hands when doing. knowing me, i probably stuff it up... touch wood.

[janoskiss]

You could try my way. It's with a permanent marker and a compass and you get an easily visible triangular pattern. You can put the optional sticky ring too. See this article (http://www.iceinspace.com.au/index.php?id=63,279,0,0,1,0) I wrote for IIS.

[EzyStyles]

arh nice method steve thanks. will give it a go :)

[davidpretorius]

steve, that is fantastic, well done, totally missed it!

[janoskiss]

Just be sure all the tools work as they should. i.e., compass and marker fit together securely, and the compass is good enough to be free of wobble and maintains its opening firmly (a lot of cheap ones are not).

[ving]

i have had my scope for quite some time now and ihavent centre spotted... my collimation (when i do it) is fine, am i missing something?

[asimov]

I don't reckon Ving. Mines not centre spotted either (12" newt) but of course, I don't use a cheshire either. Just a sight tube for the secondary & a star test for the primary.

[Starkler]

I should expand on this.

Using a cheshire, if the white ring is slightly smaller in appearance than the reflected circle of light from the cheshire and fits inside it when viewing through the end, then very small misalignments are visible allowing a high degree of collimation accuracy.

For many people close enough is good enough, but doing this will enable you will get the best high magnification views possible.

FWIW, I can see a fair amount of collimation misalignment this way before I can notice it in a star test. :shrug:

[EzyStyles]

good point geoff. i have tried a star test as well and a great amount of misalignment which you can see.

[davidpretorius]

i only use my sight tube for when i remove the primary mirror. once close, i then star test

[asimov]

At what mag Davo? I won't go under 800X these days.

[davidpretorius]

250x with the 5mm vixen. but i will soon throw in the 2.4x barlow one day.

The vixen is so goooood!

[asimov]

Yup! Kicking myself for selling it...like I knew I would!