nikonshooter Loc: Spartanburg, South Carolina

Does anyone have an idea what could be causing stars like this.

Gear Used

SCT Celestron EDGE 8HD, .70 Celestron Edge Reducer, ASI1600PRO-Mono Camera, Astronomik filters on ZWO 7 position filter wheel, Moonlite Auto Focuser.

BTW, this is not my picture.....I got it off the Jerry Lodriguss website but it closely represents stars that I was seeing when doing "Frame and Focus" in Sequence Generator Pro.

frankraney Loc: Clovis, Ca.

All the stars are that way, not just the close bright ones.

My guess, not in focus, or the lens has a film.
Have you ever cleaned a window of mirror and then looked and it was smeared s little, just needed polished again. It will cause the start effect.

nikonshooter Loc: Spartanburg, South Carolina

All of the stars in the field of view look like angels/seaguls! Mirrors are clean - took the secondary out and check it. Put it back in and collimated to a close but still way off collimation and it started to drizzle - plus being cold I decided to shut things down and pick up where I left off on a better night. Stars are as in focus and I can get ....as you focus through the seagull there is never a point where they take on a normal shape.

My guess is collimation. I will see if I can isolate the problem on a clear sky night using an eyepiece - remove as much of the optical train as possible....and get a closer collimation.

Crazy stuff happens in this hobby - thanks for you thoughts!

alberio Loc: Casa Grande AZ

Collimation was my first thought.

nikonshooter Loc: Spartanburg, South Carolina

I guess! I will get collimated and see if they disappear but ...I would not be surprised if they are still there.

frankraney Loc: Clovis, Ca.

Oops.... My bad... Didn't read well...I was thinking camera...

alberio Loc: Casa Grande AZ

Have you used the reducer before? Has it been dropped? At first I thought it might be a Hyperstar and it needed collimation, but I don't know if there is any way the .70 reducer can get out of collimation. I would do a test shot without it.

nikonshooter Loc: Spartanburg, South Carolina

Yessir......I plan to start the process of elimination. Of course I removed the camera/filterwheel and added a 8 power televue eyepiece on a diagonal to do the collimation. I have removed the secondary mirror to double check it......the primary looks fine from the secondary end. But the reducer is still on.

Thank you for helping me to dig into the possibilities!

Europa Loc: West Hills, CA

My RASA had bad seagulls, i didn’t have ones like those few really bright ones. I couldn’t get the collimation exactly right, but I did get the seagulls to mostly go away. (Celestron fixed it completely).

Something to note, after Celestron repair, I then notice an issue with tilt from my ASI1600, so if you are seeing things a bit different, in different corners, it could be that too.

nikonshooter Loc: Spartanburg, South Carolina

I will get a more precise collimation ... Changing the screws out for Bob’s knobs sure points to a collimating error being the root of the problem

alberio Loc: Casa Grande AZ

Yes, even though easy and quick for viewing, but not as precise for imaging.

Ballard Loc: Grass Valley, California

Hi Nikonshooter
Whenever you remove the correcting plate and secondary, be sure to keep the rotational orientation of all the telescope optics the same. (Usually you will find marks on the edge of the optics for this alignment). Typically on commercial telescopes the opticians will make minor corrections for a given orientation rather than correct all the components for rotational symmetry. This is also true for most camera lenses. The amount of distortion however appears to be mainly an alignment issue. I would start by removing the reducer and try a number of different eyepieces to make sure the issue is with the telescope itself. Throw a bright star out of focus with a fairly short focus eyepiece (~8mm) and adjust the optics so that the secondary shadow is perfectly centered. Then through it out of focus in the other direction the shadow should still be in the center. If not this might imply that the focus mount is not perpendicular to the rest of the optics or that the main mirror is loose or the focus mechanism that moves the primary is mechanically off and need adjustment or repair. On my C11 I had to make a tools to tighten the circular nut mirror that holds the mirror in place as the mirror had come loose ( the scope still works fine after more than 25 years).

nikonshooter Loc: Spartanburg, South Carolina

Yessir......I will be using an artificial star tonight as clouds are about to cover us in overcast and then more rain for three days. Friday and Saturday seem to be looking good! I hope to get things sorted out tonight so I do not have to waste clear sky nights fiddling with this. But then contrary to what my wife says, I don't always get my way!

Thanks for your input....I am hoping a nearly perfect collimation will remove these star shapes.

nikonshooter Loc: Spartanburg, South Carolina

I did get good to very good collimation on an artificial star. I defocused 6 wavelengths in ....then traveled through focus to 6 wavelength out. I didn't see any seagulls visually during the entire travel time...but cloudy skies tonight will prevent me from testing on a real star until this weekend. I will not know if I still have issues until then. At least I will not have to fiddle on collimation when the skies do clear.

I will update this when I have new info to let you know if the problem is solved!

Europa Loc: West Hills, CA

Could you see the seagull on the artificial star (before collimating)? Just wondering how well those work.