This is a follow-up to my previous thread:
https://app.astrobin.com/forum/topic/208401/officina-stellare-rh200-mkii-at/help-with-rh200-halosreflections
Quick update for anyone fighting RH200 arcs/reflections.
After removing the internal baffle, star shapes improved a lot 👍
But I was still getting soft, extended arcs around bright stars.
📷 Screenshot 2026-03-19 131333.png
First thought: internal reflections.
So I added extra baffling inside the tube + dew extension… but the arcs were still there.
After taking another careful look, I realised the real issue:
👉 The stock dew extension is too short
👉 Light from the outer edge of the full-aperture corrector can reach the sensor directly
So it’s not really a reflection problem — it’s direct stray light.
The fix was simple: I 3D printed a longer dew extension and made sure the outer edge of the corrector is no longer visible from the camera position.
That completely solved it.
📷 Screenshot 2026-03-19 131439.png
📷 Screenshot 2026-03-19 131524.png
Now I’m getting a clean, flat field with refractor-like stars and no more arcs 🙌
Hope this helps someone—this one took me longer than it should have 😅
📷 PXL_20260317_231855648.jpg
📷 PXL_20260317_231923385.jpg
📷 PXL_20260317_231956495.jpg
