Thanks for the response. I suspect you're probably right.
Hopefully, I figured out how to upload images here and it works.
Okay, nice images. To upload images in this forum, go to "More Reply Options" button at the lower right of your reply, then "Choose File" and "Attach This file". You can also "Add to Post".
You can see a little vignetting indicated by the "missing" part of the primary mirror not seen in the secondary. One or more clips are (or may be) missing as is the edge of the primary reflection. This is especially true if your focal plane is focused a little higher up and part of the apparent diameter of the primary extends beyond the edge of the secondary. (This is evident in your first image taken well outside the focuser, but your second image looks fine).
Your secondary is not really centered, you can see it appears to be tilted downward as seen in your image. The bottom edge is closer to the bottom of the draw tube. That's fine. Tilt it up in the direction of the blue arrow until it is closely centered on or near where the second inner red ring is seen. Tilting it up will require you rotate the secondary a little. That's okay, too.
You will also notice the secondary appears to be elliptical along 10 and 4 o'clock. After you tilt the secondary upward onto the second red ring, rotate your secondary so the primary reflection is centered "up and down" in the secondary. The secondary should be rotated so the primary reflection is also concentric with the second inner red circle. That rotation will help alleviate the elliptical appearance of the secondary and improve rotation "error". Edit
: To rotate your secondary I recommend loosening a single secondary adjustment screw in line with the focuser axis. Loosen it just enough you can rotate it be hand. I like the idea of rotating the secondary so the primary center mark falls on the secondary major axis. This ensures the primary reflection is centered "up and down". Then tighten that screw.
You could nudge the secondary a little to the right, if you need to. One way to do that is work slowly by slightly loosening the center bolt and tightening the three secondary adjustment screws. The screws should retain enough tension to hold the secondary as you gradually move it toward the primary. Repeat the small incremental movement until the secondary is equal distance from the focuser draw tube "left and right".
If you collimate your focuser axis at this point, you can evaluate your secondary position relative to the well collimated primary reflection which will necessarily be pretty much centered under the focuser. The primary reflection and secondary should be pretty much concentric with each other, and the entire primary and clips seen centered within the secondary. This means the secondary should also be pretty much centered under the focuser, too.
I cannot really make out what is happening in the dark elliptical secondary silhouette. If you primary is center marked, it should be visible in that dark area. You are using a laser, but what do you use to collimate your primary? The same laser or a collimation cap? Regardless, if you can better place and rotate your secondary, try your normal laser routine and take another picture. Or another star test.
Edited by Asbytec, 26 September 2020 - 09:43 AM.