Do I have a tilt problem?

L

lgibbons

Member
I've noticed some oblong stars in my images and initially thought I had tracking problems. When I took a closer look, I noticed that the eccentricity wasn't evenly spread across the image. That led me into looking at back focus and tilt, and -- eventually -- the FWHMEccentricity script.

I'm hoping one of you can help me interpret the data. I ran FWHMEccentricity on one of the subs from a recent session, and it seems to show increased eccentricity in the upper right-hand corner. This coincides with that I found while blinking the stack. The preview I placed in the upper right corner contained the stars that were most oblong.

I *think* this means that I have some sensor tilt in that corner, but I'm not sure. Am I interpreting this correctly?

2022-01-16_11-48-24.png
 
probably, but it's hard to say with certainty. do you have a rotator in the system? even if not if you can rotate your camera 180 degrees and see if the problem follows the rotation it could mean there is sensor tilt.

rob
 
Do the same exercise at zenith, low in east and low in west. If the eccentricity pattern remains pretty constant it’s likely to be tilt, if its minimal at zenith and swaps from east to west, you likely have some sag in the imaging train.
 
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