Collimation- grateful for some advice

[TopHouse]

It's not something totally stupid is it like, the path of your scope passes through a central heating outlet and the night you got good images the heating was either off or the scope was in a different position?

Stupid i know but I've seen stranger things on here, like telegraph wires causing unexplainable lines.

[astromerlin]

Nice one TopHouse, I wish it was but fortunatly for me all there is from my east view all around to my west view is trees, there are a couple of houses about 1/2 a mile away but thats all. I do have power cables that run across the garden but I've learned to avoid those. It did have me scratching my head last year when imaging Saturn and then I got weird things happening to the images only to find out I was trying to image through the cables.

Cheers

John

[TopHouse]

OK, next theory then, regarding an imperfection in secondary, I reckon if you held it in a light sorce and moved it about, any imperfection would show a mile off.

Do the images look poor to the eye as well as the camera when it's collimated? It's not EMF from the power cables interfering with your equipment?

This is getting like one of those logic games where the poster knows the answer and the others have to find it by asking questions lol

[acey]

When I center the focuser in the secondary reflection I get good images.

Then what's the problem? Center the focuser in the secondary reflection and enjoy the views.

If the secondary is not perfectly flat you will see astigmatism when start testing. You wouldn't notice just by looking at it. It would have no bearing on collimation questions. If you're worried about the primary then get a Ronchi eyepiece and test with that:

Telescope Testing, Ronchi Tester, EASYTESTER®

But if you already have a way of getting good images then there's no problem.

[markchrisryan]

This is similar to what I see in the collimator cap. The smallest black dot is in the center of the ring on my primary. But the circle is off in the darker area, off center.. However everything else seems lined up well and I can see all 3 clips! Does it sound as if I am well collimated? And what topics can I research to get better accuracy?