What causes this defect in a refractor? I believe backspacing is pretty well dialed in, but I’m seeing this pattern on bright stars in my subs. There is some tilt, but this happens even near the center of the frame (though it seems less pronounced there). The weird sort of shield always is on the center frame side of the star. 📷 Screenshot 2026-09-21 at 10.00.25 PM.png
Odd star pattern
