SCT collimation - should I go for better?

[x6gas]

I was quite amazed at how good the collimation of my SCT was 'out of the box'.

Visual star tests looked pretty good to me, although I am blighted by a severe chunck of astigmatism which - even when corrected by specs or contact lenses - makes this kind of judgement quite hard for me.

Anyway, in between an imaging run on Jupiter tonight I slewed to Hamal to refocus. I decided to do a quick capture on the defocused star and the result is below. I had the capture software maxed out (highest gain, maximum exposure, and 5 fps) and this is the resulting stack. Seems to show a slight skewing and my question is, is this good enough on my f/10 SCT or should I re-collimate? I ask just because the star test looked OK to my naked (and not very good) eye and I am not sure if other artifacts might be present (seeing was pretty poor when I captured this). Not sure if stacking to check collimation is even valid!

Thoughts very welcome!

[Mr Spock]

If that is in the centre of your scope's field of view then collimation is out and needs adjusting. The amount may look small but it will take a lot of detail away from objects such as Jupiter.

[Peter Drew]

Seconded!. Needs to be better.

[AndyH]

Thirded

Central shadow needs to be moved, that-a-way

Should noticably sharpen your views when adjusted.

Andy

[x6gas]

Ah ha! Thanks for the replies...

This is my HD11 with a 2x Barlow captured on an SPC880, by the way, but it seems that this will have been limiting my planetary imaging.

Thanks!

[AndyH]

My daylight rough collimation had got the startest to a similar position as in your pic.

Before adjustment, the view of Jupiter had a sort of misty washed out look. After adjustment(primary mirror in my case), the difference was like a punch to the face. Pow. Sharp contrasty image.

Whilst my scope is a Tal 200K, I'd reckon the end results for you should be similar.

Cheers,

Andy.

[Dave Smith]

I did mine recently using an artificial star (from Hubble Optics) and I found the following overlay extremely useful (and free)

Collimation

Scroll to the bottom of the page.

Here is a video demonstration.

Dave

[AndyH]

Nice links Dave.

Especially like that piece of software. Very, very clever and should be a valuable tool to those with laptops & webcams.

The guy 'sounds' frozen, if that's possible.

Andy.

[Merlin66]

This is where the Bob's Knobs can make the job that much easier (and safer!)