collimating 8in SCT

[AstroTiger]

Hi guys

i have a small issue with this.

I have the bobs knobs also. The main problem is though wen i try to defocus, it seems to also have the effect of rotating the mirror?

anyone have any ideas on how best to remedy this?

Cheers

AT

oh and ps, collimation is achieved wen the dark spot is centred in the image right?

thanks

[centroid]

Can't and that I've ever noticed the mirror rotation effect that you describe, on my 10" Meade SCT :?

With the defocused star, the dark spot should indeed be centred and the the rings around it should be perfectly circular, and symetric around the centre area and each other.

Dave

[Martin 2]

You do get movement of the image as you go through the collimation process, just use the slew buttons to re-centre it as needed.

M2

[Albireo380]

I have "Bob's knobs installed and can't say I have ever had mirror rotation with my 8" LX90.

Have a look at these 2 web sites - the first shows what you would expect to see when collimating your SCT.

The second tells you how to roughly collimate in daylight - much to my surprise, it seems to work

http://legault.club.fr/collim.html

http://www.mira.org/ascc/pages/lectures/collim.htm

Tom

[Kai]

You do get movement of the image as you go through the collimation process, just use the slew buttons to re-centre it as needed.

M2

Me as well on my C8

[Talitha]

You do get movement of the image as you go through the collimation process, just use the slew buttons to re-centre it as needed.

M2

Me as well on my C8

Me too, on the LX-10 and previously on my old Ultima 2000.