53 replies to this topic

[Kfedorov]

Was trying to handle the sensor tilt using astap. However, results were inconsistent. I don’t have enough stars - one corner always seemed to have too few stars and it would grab stars further out showing flat on 3 corners and the 4th corner was way off. Never had issues before because I could always point at the Milky Way (rich star field). However galaxy season, this is not convenient. So I ordered a sensor laser device from Astro Precision. Should get the device shortly. If the adjusted sensor tilt and recollimating the secondary doesn’t clear this up, probably need to get a scope laser collimator and see what’s out of alignment.

Just checked out the Astro Precision website, not really sure how it works, but let us know if it works.

 

I was also thinking about the Hotech collimator kit.  I think it can also determine lateral misalignment of the corrector plate. Corrector tilt thankfully has no effect on the stars.

Edited by Kfedorov, 12 June 2025 - 03:11 PM.

[andylast]

is it something to this effect? 

https://www.cloudyni...2#entry13992026

 

I know the rings are not concentric but may be stemming from the same problem. In the thread we were talking about short baffles on the 14" and 16"  ACF and the light it passes through.

 

Which ACF do you have?  Are the rings perfectly concentric with the star?

 

Maybe it could also be caused by turned down edge or the mirror edge bevel, reflections from baffle rings...

Its an f/10 14" ACF. The rings (reportedly) show up at a distance from a bright star, concentric and surrounding the star. Visible in images, and in the eyepiece. I have a 14" f/10 to test and am putting the feelers out first to see what others have experienced, and whether it can have anything to do with internal reflections due to this radially off-set problem you are discussing.

[Kfedorov]

Its an f/10 14" ACF. The rings (reportedly) show up at a distance from a bright star, concentric and surrounding the star. Visible in images, and in the eyepiece. I have a 14" f/10 to test and am putting the feelers out first to see what others have experienced, and whether it can have anything to do with internal reflections due to this radially off-set problem you are discussing.

Did you check the links on page 2 of this thread? Anything similar to that issue?

[andylast]

Did you check the links on page 2 of this thread? Anything similar to that issue?

Those are the ones. Yes, I have seen those posts before. There are one or two similar posts I have seen in the past about it. One guy sent his scope back to Meade. It was returned, claimed fixed, but I think he still had an issue. Not sure that the culprit has been fully identified, some ideas, but got the impression that as Meade didn't say exactly what was wrong, it remained unsolved. The one I have is claimed to show the ring in an eyepiece, which rules out sensor reflection. I saw your post about radial off-set, and wondered could this also cause an internal reflection that might result in a ring surrounding a brighter star. Just looking at known issues to identify what the cause can be. Have yet to look through this one. I have an old CGE which will hold it, but need at least two nights and days of clear weather, so the scope can live for at least 50+ hours on the mount without needing to take it off. In the UK, that doesn't occur that often.