RC alignment

[E_ri_k]

Hey guys, sorry if I'm asking a dumb question, but I don't know weather I'm being super picky or not, but I'm not happy with the collimation of my RC10. I have a Takahashi collimation scope, which threads into my Moonlite focuser. Collimation between the Takahashi, and star test don't match? I can get the scope as close as to what I could say is "perfect", but on star testing, it just looks out by a little? And vise versa, perfect star test, and the Takahashi is out by a little?

It doesn't seem logical, any ideas? I don't know how to proceed :screwy:?

Thakns.
Erik

[Paul Haese]

What are you using to hold the eyepiece or camera in position? Is it a compression ring? If not then this is the basic star. It is preferable to screw fix a camera to get good consistent results for collimating RC scopes.

I think you ought to do a star test and collimation with the camera in place and then collimate that way. The Tak scope will get you close but it still needs a star collimation to get it perfect.

[E_ri_k]

Thanks for the reply Paul. Im using a compression ring to secure eyepiece/camera. I had a play tonight before the clouds set in, and got really nice concentric rings. Screwed the Tak scope in, and the centre spot was way off. One thing I'm considering is that the centre spot on the secondary may not be exactly centred?

A good star test would surly be more trustworthy than a collimation tool?

I'll see what I have to screw in an eyepiece/camera and try that and see if it makes a difference.

Thanks.
Erik

[Paul Haese]

Yes star testing is the best way to collimate. The center spot may well be in the wrong position.

[E_ri_k]

The centre spot must be in the wrong position, I went out again tonight and screwed everything together, no compression rings. I managed to see the Airy disc around Canopus :eyepop:

Feel a bit silly if that is what it was all along....
Erik

[Paul Haese]

Don't feel that way, not your fault.:)

[Den]

Hi Erik,

Dont forget about the focuser also being on centre to secondary, not sure if your RC's focuser can be centered or if you can put a shim in.
Check my post there is a RC being centered with a laser (focuser end) and you can mark the centre on the secondary cap (cover) on secondary housing.

See link.
http://www.iceinspace.com.au/forum/showthread.php?t=103784

Den

[E_ri_k]

Thanks Paul! I guess I just didn't expect it. Wold have thought the factory could have placed the spot properly haha.

I did notice that collimation shifts when the focuser rotates. I have Moonnlite focuser on it. I'm not sure if you can adjust the centring of it, but I'll check it out.

I am pretty confident I have it right though.

Erik