Having major issue!!

[Willarnold]

I've put some bobs knobs on my sct to collimate, but i'm completely stuck!! the secondary is now way out, and I could really use some help and advice.

Tips and links welcome

[Peter Drew]

Hello Will.

This is almost inevitable when fitting Bobs Knobs as you can only fit one at a time. Thankfully there is only one component to work on. If you remove the eyepiece in daylight and look in through the back you will see the secondary mirror. When this is correctly collimated you would see a thin black annulus round the secondary which is a reflection of the secondary cell. What you now have is probably an image showing this annulus significantly offset with one edge noticeably thicker than the other. If you screw in the knob that is orientated with this thick edge it should start to make it more symmetrical, it's quite a delicate adjustment so take it slowly. Once you have got things nice and concentric, the scope should be collimated well enough for the usual star test adjustments to get it spot on. Hope this helps.

[Willarnold]

Thanks Peter, I gave up in the end last night! I'll give it a go in the daylight

[nightfisher]

http://www.robincasady.com/Astro/myimages/collim.html

This is a really helpful site, worked for me when i had to collimate my omc 140

[Willarnold]

Done it, really easy and quickly in the daytime!!! Although it's the opposite to your instructions, I.e. you loosen the side with the larger dark ring

It was waay out, no wonder I could hardly see stars, and they looked like comments

Kind regards

[Willarnold]

Stupid iPad and it's auto spell. Comets not comments