Tilt or spacing?

[spectre]

Hi all,
I haven't posted in a while due to the lousy weather here in Pa. This is an image of NGC7209 I took this weekend trying to get the spacing correct for my DSLR and focal reducer. This is 67, 60 sec. subs, guided, ISO 800 taken thru the C-8 using the f6.3 reducer, riding on the CG-5. I have been trying to diagnose the elongated star shapes in the corners of the image and I think it is a spacing issue, but it may be sensor tilt as well. I have tried increasing the spacing and the elongation gets worse. I have reduced the spacing as much as I can using a thin T-ring but I can't get the spacing any shorter. Is there such a thing as a short T-adapter?
All processing was done in PI, resized in PS for posting. My processing skills need some work but I'm slowly getting there.

C/C welcome and encouraged
Clear skies
John

[JayTee]

There are two pieces of software you can use to analyze your image plane. The first is CCD Inspector I think it has a 30-day free trial., The next is MaxSelector and it should be freeware. Both of these titles put out a graphic depiction of your image plane and how warped or not warped it is.

Cheers,
JT

[spectre]

Thanks JT. I've heard of CCD Inspector but not MaxSelector. I'll check it out.

[yobbo89]

yeah looks like tilt related to me .

[spectre]

Finally had a chance to check out both of those programs and they both tell me the same thing, I've got tilt from the upper right to lower left corners. Now to figure out how to correct it.
Thanks for pointing out those programs.
John