Anyone in Adelaide help with SCT Collimation?

[Wookie]

Hi All,

I've recently acquired my first SCT but would really love some help with collimation.
I have done a star test and adjusted the secondary mirror to airy disk symmetry but images still do not look sharp (i.e stars are not pin point).
I am confident in collimating reflectors but the SCT is a different beast.
I have a HoTech laser collimator.

If anyone is based in Adelaide and would be kind enough to assist, I would be extremely grateful.

Thanks for reading.

Ryan

[Wavytone]

Hi Ryan try this link http://www.telescope-optics.net/diffraction_pattern_and_aberrations .htm

- scroll to the bottom. Of the images 1-9 which resembles what you’re seeing ?

Hate say this but SCTs are a compromise.

[Wookie]

Thanks for that.
I'll have to get the camera and sct under a good seeing night (which is rare with the weather in Adelaide lately) and compare against those.
Sometimes it's easier to get someone with an experienced eye to show you the way.

[byronpaul]

Wavytone,

Thanks for sharing this link ..... great resource 👍

Paul

[Merlin66]

You can always use the Ronchi grating to get a quick view of the optical train and identify any issues.....

[Rkonrad]

I must add that I never got that crisp view with any SCT like one gets with a Refractor or Mac I only had SCT up to 8 inch and a 102 Apo as well as my 150 Mac so my comparison is limited

[glend]

A Duncan Mask works very well for SCT collimation, and is easy to make yourself. You can download the instructions from the Net. It is very useful for collimation with a camera.

[Wookie]

I appreciate the response and have learned a lot of new info from research of your great replies.

I have ordered an artificial star and will give the Duncan Mask a go.

Thanks all.

[SkyWatch]

Hi Ryan,

What sort of diagonal do you use? I have a Celestron CPC 800, and the images were always "soft" even with proper collimation until I replaced the stock 1 1/4" prism diagonal with a GSO 2" one. After that I got "textbook" stars...

Other than that, I live in Adelaide (southern), and am happy to assist if I can. Send me a PM if you like.

All the best,

Dean

[Wookie]

Thanks Dean,

I'll send you a PM to discuss.

I am not using a diagonal.

I do have a William Optics 2" but thought I'd take out any additional accessories in the optical path for collimation first.

Talk soon.

Ryan