Re: [APML] Help! Advice on collimating a C14

["Steve Walters" <s-walters@comcast.net>]

Andy,

>From your description, it sounds like the secondary screws are not properly 
snugged up. You have to have all 3 tight or the secondary will flop around. 
It's sitting on a "cone" so it can be tilted by the 3 screws, if you tighten 
one, you have to loosen the others. At least many of the newer SCTs are made 
this way, older ones had springs on each of the screws.

On my website, there is a simplified procedure that may help you collimate. 
It tells you which screw to turn and in which direction based on the image 
seen when viewing a defocused star. It always keeps you moving in the right 
direction without having to guess what to do next.

Steve...
www.StarryNights.us

----- Original Message ----- 
From: "Andrew Clegg" <andy@w4je.com>
To: "Discussion of Film Astrophotography" <astro-photo@seds.org>
Sent: Monday, November 29, 2004 12:29 AM
Subject: [APML] Help! Advice on collimating a C14


> Gang,
>
> This may not be the best place to ask this question, since everyone seems 
> to
> use RCs or refractors, but I thought I'd ask anyway...
>
> I have a C14 CGE, and I am having one &$%#^ of a time getting the thing
> collimated. Deep sky views are spectacular, but lunar and planetary views
> are basically horrible (my Orion ED80 gives better views). This is
> frustrating because in the reviews of the C14 CGE that I've read, they 
> often
> mention that the 'scope provides some of the best lunar and planetary 
> images
> the reviewers have ever seen.
>
> As I eventually want to move past piggyback astrophotos to shooting 
> through
> the C14 itself, I need to find a way to get good collimation. I've tried
> collimating on stars (with the help of a friend), but the process is very
> slow, tedious, and frustrating (even with Bob's Knobs), and never ends up
> with greatly improved images. And when the 'scope is packed up for the
> night, collimation is lost, and the next observing session is once again
> spent mostly on collimation, in a vein attempt to improve the images. 
> Arghh.
>
> I've read almost everything I can on the tricks of star collimation, but 
> it
> just ain't working for me. So the next option is one of the specialized
> laser collimators for SCTs, which shine through the optical path of the 
> SCT
> in reverse and project a scattered laser spot onto a distant target. I
> wouldn't mind trying that, but I really would like to know if anyone has 
> any
> experience collimating SCTs (either with a laser or something else) before 
> I
> shell out $200 for the laser collimator. Another choice would be 
> collimating
> on an artificial star, but again, it would be good to hear some opinions
> before sitting down at the workbench to make one of these.
>
> Has anyone had the same trouble as me getting a large SCT collimated? 
> Should
> I send the OTA back to Celestron to make sure there isn't something wrong
> with the optics? That would cost me a couple hundred bucks, but it would 
> be
> worth it if that would cure my problems.
>
> Help!
>
> Clear skies,
> Andy
> www.w4je.com
>
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