I defocused the star a little more so I'd get a bigger donut with more detail in it.. I don't know what that bright dot is in the center either. Could it be because my 0.63 reducer was on, while the mask is designed for the full focal length?
There's something messed up in your image train, like a light leak or reflection or maybe your image train is OK, but you've really cranked up the gain to obtain this image. I had a 0.63 Celestron Focal Reducer as well when I used my mask and I've never seen this.
Furthermore, you're too far out of focus to know whether you are collimated or not. The central obstruction image, i.e. image with a doughnut, only tells you that you are way off. You need to go more into focus to check. For example, here's my video of what you should see as you go in and out of focus:
There are literally circles around a bright dot as you move in and out of focus. If the circles on average are symmetric around the bright spot, you are collimated. As you can see it's a real PITA to actually judge this, that's one of the the reasons why I created the TriBahtinov.
Edited by cytan299, 21 July 2022 - 07:46 AM.