Collimation...

[doug]

     Pleeease ..... has anybody got a laser collimator that I could borrow to "do" my 1145 reflector.  I cannot get on with the Cheshire collimator, but I may have more success with a laser type.

     I tried to collimate the scope with a laser collimator at the last Kelling Heath session last year, but the collimator itself was way out .....
 
     So I need some help ............

     Doug.

[Ian]

Quis collimatiet ipsos collimates?

Sorry, couldn't help that. Feeling a bit better now.

Can't help with the laser collimator Doug, but what was the problem with the Cheshire? There's a certain amount of interpreting needed to work out what you're looking at, but even so I've found mine pretty straightforward to use.

[doug]

      Thanks. Ian.  I shall have to call on your obvious expertise, then. You can demonstrate the working of a Cheshire collimator to me some time.  I really do need assistance..... I did try collimating the scope with the Cheshire, and at all went horribly wrong; God knows what I managed to mangle. but I managed something. 

      Perhaps I could beg your help one clear skies day ......... yeah??????

      Doug. 
     

[Mike]

I have a laser collimator you can borrow Doug. I think you've borrowed it before.

[Carole]

If this is any help.

I took Doug's reflector down to DSC and showed it to Mark, Mac, Duncan and Chris, they said that the secondary mirror was way out.  They thought the primary mirror was OK.

Carole

[Mike]

Collimating the secondary is the easy bit.

[Ian]

I certainly can help out,but it's easier in a really well lit room. I did have a useful guide website once, I'll see if I can find it again. The most important thing is to start with the outside ring (the end of the focusser (or cheshire if it's a short tube) and work inwards centring them as you go. It's tempting to just align the crosshairs, but that really isn't any good unless you are lucky enough to have collimation spot on.

Your primary does have a centre marker of some sort?

[The Thing]

The secondary was rotated away from the drawtube hole. I think someone had undone the centre screw by mistake. Once that's aligned collimation should be achievable.

[Mac]

Your primary does have a centre marker of some sort?

when we looked at it at quagmire common. The primary did have the centre marked with the ring.

Mac.

[mickw]

Here's a video

http://www.youtube.com/watch?v=ME-CBtemo7Q

There was also some useful sites that were suggested when I was trying to sort out the lightbridge - If I find them I'll post them.

OK, this was from the Pimp my Dob thread and suggested by Ian - How to use a Cheshire - and it works 

http://www.propermotion.com/jwreed/ATM/Collimate/Chesire.htm

[doug]

     Thanks very much, all you knowledgeable people.  The Cheshire diagrams are very useful, as is the video for the laser collimator.  I  would like to borrow your laser please Mike; I MAY have more success with that than the Cheshire.

     Doug.