Andyy

This is a very common problem with WO and other telescopes made by the same manufacturer under different names. It’s well documented online in several different forums. If I remember correctly it’s something to do with how the lens cells are retained inside the OTA. The problem gets worse in cold weather.

Perfect!

Thanks! The setting is "ON" But what happens then if I've used frame wizard and framed slightly off target center

I'm pretty sure NINA plate solves after meridian flip. I thought maybe it was an operator error but seems like a common issue:

Good to know. Almost never do meridian flip

There is no way this can happen. It's screw connection and it is very tight. I've checked

Yes, exactly but I did not touch camera (or mount). NINA did the automatic flip. I did not plate solve after flip

Uneven black border around image after stacking. A thin black border due to dithering is ok, but is this normal? It happens last night when doing automatic meridian flip in NINA. I've stacked subs before and after meridian flip and only show a small thin border caused by dithering. Only when I stack all subs toghether I get this result.

Thanks! I’ll start all over with the secondary tonight. It’s almost there now! I’m not a beginner in this hobby, just beginner with newtonians Thanks again @alacant you are a great resource here!

@alacant The Telia-linkis broken… I tilted the mirror upwards to center the reflection in the mirror under the focuser. Isn’t it best to keep the secondary mirror stalk straight and «paralell»to the primary mirror? …or it will result in this, either left or right. In my case; up or down.

Used a mirror and inspected the secondary stalk and found the secondary mirror was slightly tilted upwards towards the focuser. This might explain the uneven field. I’ve spent a lot of time trying to center the secondary under the focuser with an offset. I’m not sure if I’m quite there, and may have tilted the secondary mirror because of this (to compensate). Feel free to chime in if you have a good technique for centering the secondary mirror with an offset without causing tilt!

Got all necessary collimation tools and collimation looks spot on. Vignetting is remove with calibration. Star field look even and stars are round all the way to the corners. Probably just a hair off regarding tilt. «Problem» is that I’m a perfectionist

Collimation looks perfect but the vignetting is still uneven. I’ll give collimation another try! camera is rotated physically not with software.

Lets say the the secondary is tilted causing vignetting on one side of sensor then wouldn’t the vignetting be stationary on that same side/place independent of sensor orientation?

The vignetting pattern is still stronger (darker) on one side than the other. If you see my drawing there is to different shades of gray (top and bottom). Pattern is following the top part of the sensor as it turn around 180 degrees.

Sorry, correction camera is rotated 180 degrees of course. My bad, it was late… I think the problem is camera-side (most likely coma corrector) not collimation.

If the secondary mirror is the problem, wouldn’t the vignetting pattern stay the same even when camera is rotated?

As seen on laptop screen: Camera and coma corrector is rotated together. I can also see the same vignetting pattern on a singel light frame. I use filters with filterwheel. Pattern is same for all filters.

Help my flats are uneven with newtonian. The flats are darker on right side than left side (horizontally) but flips when I turn my camera 180 degrees. What does that say me? I need Help thinking I can't get me head around

Tried that did help very very slightly but I think there is something else going on here. Most likely collimation... Update: Collimation fixed it!

Hi! I've been using OAG for a long time now, but recently moved from 1.25" filter to 31mm for my 4/3 sensor. Now my OAG prism stalk cause slight vignetting (shadow) in one of the corners. My question is does this shadow calibrate out with flats or do I have to move the prism?

I came over this thread which relate to your problem: AT60ED - pinched optics? - Beginning Deep Sky Imaging - Cloudy Nights A possible solution is described on page 2 of this thread.

To be clear my understanding of pinched optics is that something mechanical puts stress on glass and cause artifacts usually triangular star shapes. Pinched optics I have seen on Esprit but not mechanical parts protuding into the light path. It doesen’t suprise me though these cheap scopes all have their quirks. Some more expensive ones have them too… We are at pixel peeping level here… I want to say great image @Philip Terry keep up the good work!

Use aperture mask. I used a 3D-printer to make one, but for testing just make one out of cardboard. This will help on star shape.

The Esprit does not have this problem not that I know of anyway. We agree something is entering the light path causing the artifact maybe spacers. It’s not serviceable by the end user. I made a aperture mask on my telescope to fix the problem. It made the telescope slightly slower but stars were nice and round.