Jump to content


Collimating a C11

Recommended Posts

The 3 screws on the outside of the secondary housing adjust the collimation.

Look at a defocussed star, if in collimation it will be circular with nice rings, if out of collimation it may be deformed and the rings will not be circular. Adjust the screws at the front to regain a nice circular pattern.

The screws only require VERY small adjustments so don't go mad. Even better buy yourself a set of Bobs Knobs and replace the screws with thumbscrew types which dont need a screwdriver and adjust by hand. Never replace more than 1 screw at a time though or the secondary will come loose and you will need to remove the whole front corrector, not the easiest of jobs!

Once you've done it a few times it becomes quite straightforward and you get used to which screws move the image in which direction. Best to give yourself about half an hour though until you are practiced at at.



Link to comment
Share on other sites

I sometimes find that it is easier to collimate on the planet itself as it is not affected as much by seeing as a star. Slightly defocus the image and a "halo" will appear which will decentre if the collimation is out. Use the 3 secondary mirror adjustment screws as already mentioned. Make sure that the image is centered in the field of view or it will appear miscollimated.

Link to comment
Share on other sites

There is a way to do it using a hartmann mask that is very accurate.

I've got it in an old 'Practical Astronomer' magazine somewhere.

I'll dig it out and send you a copy if you want.



Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.