Collimating a C11

[Helen]

I think I need to collimate the C11 - any hints or tips, or recommendations for software help? I'm hoping to get some detail on Jupiter later

Thanks

Helen

[Paxo]

Helen,

CCD inspector has a defoccused star image collimation routine which is very easy to use (similar to standard defocussed techniques). There are also collimation routines for doing collimatiom while in-focus as well. Software is also available as a 30 day trial if you want to take a look:

Welcome to CCDWare - CCDInspector

Steve..

[ncjunk]

Does anyone have a brief how to without the aid of software? Which bits do you adjust on these scopes?

[Rossco72]

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.

Regards

Stuart

[Peter Drew]

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.

[Helen]

Thanks all. I'll let you know how I get on.

Helen

[RobH]

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.

Cheers

Rob

[skybadger]

Hi Rob

I'd be interested in that if you wouldn't mind

Cheers

Mike

[ncjunk]

Stuart: great overview thanks! I thought it was those screws but didnt want to muck it up.