Orpington Astronomical Society

Astronomy => Technical => Topic started by: Tony G on May 11, 2009, 12:17:05

Title: Collimating a Mak-Cass.
Post by: Tony G on May 11, 2009, 12:17:05
Well I managed to set up the mount towards the end of last week and tried the Phenix with the new crayford and slightly shortened tube, and wished I'd never touched it. :-?
it's not the same, as I now have some colour dispersion, so I need to check the lens again, and we'll see if that helps.
The real reason for this post was the collimating of the skymax pro, (in Chris's absence). I tried this after the phenix was mothballed, and come to the conclusion that it is seriously out of collimation, and was thinking about taking the Phenix back out  :).
As I have never collimated anything before (didn't see any reason to) and not having anything like a laser collimator to collimate the scope with, I am now asking for HELP!
When you go onto the tinternet, there are various different ways to do this task, but each seem to contradict each other with some saying you cannot use a laser on Mak-Cass's or SCT and some only using this method.
Please help this poor unforunate amatuer astronomer with no scopes (except the WO66) to be able to see the heavens again without it looking like a 3D image without the glasses (phenix) or a view of Saturn which resembles a new planet in our solar system.  :o

Tony G

PS....................This is a serious post.
Title: Re: Collimating a Mak-Cass.
Post by: RobertM on May 11, 2009, 13:38:58
Hi Tony,

After looking at how it's constructed, it cannot be collimated by laser.  The best method is by test against either a real or artificial star.

The reason that SCT's (and some Mak Cassegrains such as Intes) can be successfully be collimated with a laser is that the secondary is an adjustable part of the system.  The laser can be bounced back to the collimator in the eyepiece holder precisely by adjusting the secondary screws.  Your SkyMax does not have an adjustable secondary, in fact the whole front meniscus lens is fixed at factory and should never be adjusted.  Instead adjustment is via the primary via three set screws.

I've never done one of these but it should be much easier than my SCT.  I'm more than willing to have a go if you want to bring it around (will also me the chance to check out the optics).

Robert
Title: Re: Collimating a Mak-Cass.
Post by: Tony G on May 11, 2009, 15:48:56
Hi Robert,

Thanks for the offer, if you PM me with your address, I'll pop round when its convenient with you.

Thanks again.

Tony G
Title: Re: Collimating a Mak-Cass.
Post by: Fay on May 11, 2009, 16:31:45
Oh Tony, I do hope you get it sorted, what a nightmare. I did have a little chuckle, just a little one, about the 3 D image without the glasses.

I wish I could help you.


Fay
Title: Re: Collimating a Mak-Cass.
Post by: Tony G on May 11, 2009, 16:53:00
Well if this all fails Fay, it maybe a new scope, (which I've already got my eye on :D)
I'll just have to tell Flis to cut back on the champagne, and that fish egg thingy she likes with ritz biscuits, to make way for the new addition.
And I won't be getting it off ebay where Flis gets the Spanish Champagne from as I think it tastes like Bulmers Cider, come to think about it........................... :roll:

Tony G
Title: Re: Collimating a Mak-Cass.
Post by: doug on May 12, 2009, 08:33:46

     What `scope haveya gotcha eye on, Tony??  Meade has gears made of cheese, according to some sources, but MY ETX70 didn`t have stripped gears; the drive motor chassis was broken by being moved when locked on to the Moon.  It is now in pieces and I have a nice Meade 70mm tube, which I shall mount on a something or other ??!!??****??>:< :o
Title: Re: Collimating a Mak-Cass.
Post by: doug on May 12, 2009, 08:37:56

     ......... and sorry, Rick.  I seemed to have hi-jacked a thread with a totally different subject.  Oh, Gawd, another mangle :(
Title: Re: Collimating a Mak-Cass.
Post by: Tony G on May 12, 2009, 09:31:25
Doug,

The Skywatcher 120 ED PRO refractor.  ;)

We'll have to wait a bit though, as the car is in the garage, and they haven't told me the cost of that yet.  :(

Tony G
Title: Re: Collimating a Mak-Cass.
Post by: doug on May 12, 2009, 10:36:29

     I think that I am getting a SkyWatcher 102 SynScan for my birthday ........ I hope...... I hope!! :)
Title: Re: Collimating a Mak-Cass.
Post by: Tony G on May 13, 2009, 10:31:18
Thanks Robert,

this thread is no longer required.   ;)

Tony G
Title: Re: Collimating a Mak-Cass.
Post by: RobertM on May 13, 2009, 12:11:33
No problem Tony.  It might be a good idea to check it again at the next DSC, assuming the weather get's over Fay's new acquisition by then that is !
Title: Re: Collimating a Mak-Cass.
Post by: Rocket Pooch on May 14, 2009, 13:08:46
Well done Robert, Tony, did the screws fit in ok, and had the hacksaw gone away ?
Title: Re: Collimating a Mak-Cass.
Post by: Tony G on May 14, 2009, 22:54:38
Chris,

The screws fitted fine, and hopefully I have learnt my lesson, and will never have to loosen them again.  ;)

Tony G