PLease help me decipher CCD Inspector to cure my issues!!

[swag72]

Following on from this thread http://stargazerslounge.com/imaging-discussion/178225-elongated-stars-im-sick-death-them.html I have downloaded CCD Inspector in a bid to cure my problems once and for all. However, it leads me to more confusion!

Please find below the CCD charts and the image it was taken from - A 30s exposure with Dubhe being the bright star.

What are your thoughts on these? I thought they looked quite good and show absolutely no issues with my focuser not being square or sagging etc. (If I'm reading them right!)

[swag72]

Now may I move onto my 300s guided pics - Oh dear!! Perhaps people can give me an idea what is going on? In my mind, the 30s and 300s should be the same IF the problem is my focuser as I think it is.

[Komet]

It is best not to have a big bright star in the centre of the image. You really need a nice plain starfield with stars all over the view. You should see what CCD Inspector makes of M42!

[swag72]

So has the bright star affected the results? I can go out and do some more, but surely the problem manifesting itself will be the same?

[swag72]

Taking on board Micks advice, I have gone out again, moved position and refocused. Now I am really confiused. I took 30s exposures again - Perhaps someone can suggest why these CCD Inpector charts are so different from the first post, which were also 30s.

The scope has moved to a differnt position, the focus has been altered - That's it. Surely they should be the same?

Utterly confused and angry now - What the hell is going on?

[lukebl]

Sorry, can't help, but like you I am now frantically using CCD Inspector to try and sort out my similar probs. The weirdest thing is that I get completely different curvature results for identical 30s exposures.

[swag72]

It's not only me then Luke!! Hope you get to the bottom of it.

[ianaiken]

Me too, it's driving me nuts. I even tried guiding when taking the subs. Tilt is all over the place and my stars are eggy. Maybe a new focuser is needed. I'm going out now to do some more testing while its not overly brilliant.

[swag72]

Can anyone please take a look at these and suggest what is happening with the orthogonality of my imaging setup?

[r3i]

As Mick (Komet) suggested, you need to be pointing at a rich starfield so that CCDI has hundreds if not thousands of stars to analyse.

Your tests had just 37, 70 & 80 stars in them which isn't really enough for CCDI to get stuck into and to give a consistent result.

Try pointing your scope at somewhere in the Milky Way and see what you get.

[themos]

The scope has moved to a differnt position

So what happens when the scope does NOT move to a different position?

Everything I've heard so far points to some shifting in the "image train" as you point at different directions.

Take a shot at the zenith, guided and unguided, so that Inspector sees hundreds of stars. Use your DSLR for this, gives you more stars. If you don't see a tilt difference between guided and unguided (I am betting you won't), substitute the CCD and try the same procedure, always pointing at zenith.

You just have to reduce the number of variables.

[swag72]

I can put on my 1000D, but that will bring other issues that I have never sorted out - I know that my field isn't flat, I have not been able to fix it - Using the Atik meant that I pretty much was imaging within the area that wasn't giving me problems.

I think if I introduce the 1000D into the mix there will be all sorts of additional problems, but I'll give it a go next time I am out. Then we really will have problems to sort out!!

When I put the 1000D on the scope, do I add the reducer / flattener or not? Without it the field will be very unflat indeed I would imagine!!

[themos]

Not flat is ok, I think, as we are really trying to find a tilt component to the problems. But you are right, we need to stay with the Atik as much as possible. I'd say try to eliminate any pointing differences first so always shoot at the zenith while you try realigning the focuser mating to the tube. Or perhaps concentrate on shots of Polaris region which is at fixed altitude and shouldn't require guiding assistance.

[SteveA]

Apologies for hijacking this thread for a fairly basic question on CCD Inspector....

I had not heard of the software until reading this thread ..

So...I'm just looking at website contemplating a download...

Is this application for real?? Can I really use it to colllimate my scope using my camera....this all sounds too good to be true!

[themos]

MetaGuide does that for free.

[Mike Hawtin]

MetaGuide does that for free.

Quite right, plus it can re-centre the subject star after each adjustment, just stay at the collimation screw end of the scope and watch the screen!

[SteveA]

Oh..Happy days!..

Thanks for that chaps.....I will definately be giving that a go.

[Komet]

MetaGuide does that for free.

Video camera only though isn't it?

[themos]

webcam, yes.

[Komet]

So no good at all trying to collimate with a fully loaded camera/wheel/oag then.

[themos]

no, no good at all

?