What Does This Mean?

[KenMiller]

Discovered CCDInspector.
Ran it on an image from my E-180.
Haven't read the manual yet
How's this look?

[Spoonsize]

I'm far from an expert, but it looks to me like your ccd camera is tilted a small bit from orthoganal(sp) and you are a smaller bit away from perfect collimation.
Cooboration from another would be good before you accept what I say.
Steve

[neilfleming]

This shows that your E-180 is very nicely collimated! Yes, there is an orthogonality issue. It also shows a fair bit of field curvature. Try looking at the result from the button immediately below the one you pressed to get that result. Here is the version from my TOA-150 with the FF:
http://autostarsuite.net/photos/hoser/picture7484.aspx

...Neil

[budguinn]

Hi, Ken,

It actually looks pretty good as far as the imaging train goes. The tilt is perfect, and the collimation is so close it is not an issue. The curvature shows off by a bunch because...and this is just a guess...you either shot something with a nebula, galaxy or strong cluster in it. When I check one of these objects with CCDInspector (I also have a 180ED) it shows about the same....but when I do the exact same thing...the same night and imaging setup, of a very open cluster or star field it shows a very flat field.
You can't get really good readings unless it is just a very nice wide star field....without nebula or galaxies in it.

hope this helps,

bud

[KenMiller]

That helped a lot Bud! Thanks.

You were right - that shot had a bright nebula in the middle.

I went back and ran it on an open cluster I shot the same night and the curviture is greatly reduced. The other metrics were improved too. Of course this raises the question about believability of any results.

CCDInspector's algorithm(s) is/are proprietary but almost certainly utilize Zernike Polynomials. I'm still researching this, but it appears that the application of Zernike's to characterize optics is frought with potential issues - for example, the presence of air turbulence entirely invalidates any results.

To quote one paper, "The blind use of Zernike polynomials to represent test results can lead to disastrous results."

It's not a high priority right now, but when I get a chance I'll dig into this further.

[neilfleming]

CCDInspector will also not handle undersampled resolutions, like those from my FSQ or TOA-150.

...Neil

[KenMiller]

What do you mean Neil when you say "undersampled resolutions?"