Warning about GSO Ritchey-Chrétien's Baffling ( RC resold under Orion, TS-Optics, .. )

(Before you use the contact form on this website, I don’t know if recent models are shipped with baffles. I’ve heard conflicting statements. Perhaps re-sellers are adding them.

I know there are now various sellers of RC baffles using these specifications. I also cannot personally vouch for any of these as I have not tested them, nor do I have RC telescopes of various sizes to test them with)

Description

Ritchey-Chrétien telescopes by GSO, Guan Sheng Optical, are a popular option in the medium price range. They are resold by various retailers, such as Teleskop-Express/Teleskop-Service, Orion, iOptron, Astro-Tech, Apertura, TPO, and others. They unfortunately suffer from a optical design problem which limits their use. With the primary mirror baffling issue corrected, they are good telescopes with excellent value (I use a corrected RC myself in my own observatory), but the baffling design flaw introduces significant problems “as-purchased”, especially during bright moonlight.

► Thank you to:

Dave Rowe for demonstrating the raytracing and verifying calculations.

Tõnis Eenmäe for suggesting tertiary baffling to better prevent internal reflections.

► Specifications:

RC6 (f/9):

• Extend baffling edge 136mm from primary mirror (= 11mm from current baffling) (x-axis)
• Extend baffling ~2.3mm (+-0.25mm) inwards from current baffling (not optional! Only extending 11mm would cut into on-axis light reflected by the primary, orange ray 1:55 ) (y-axis)

RC8:

• Extend baffling edge 175mm from primary mirror (= 25mm from current baffling) (x-axis)
• (Extend baffling ~2mm (+-0.25mm) inwards from current baffling (minor difference, optional)) (y-axis)

The RC8 is least affected with longer existing baffling, though it’s far from perfect.

RC10:

• Extend baffling edge 243.4mm from primary mirror (= 51mm from current baffling) (x-axis)
• (Extend baffling ~1.5mm (+-0.5mm) inwards from current baffling (minor difference, optional)) (y-axis)

RC12:

• Extend baffling edge 344.3mm from primary mirror center (= 44mm from current baffling) (x-axis)
• No inwards extension needed (y-axis)

RC14:

• Extend baffling edge 417mm from primary mirror center (= 103mm from current baffling) (x-axis)
• Extend baffling ~9mm (+-0.5mm) inwards from current baffling (not optional! Only extending 103mm would cut into on-axis light reflected by the primary, orange ray 1:55 ) (y-axis)

RC16:

• Extend baffling edge 420mm from primary mirror center (= 68.5mm from current baffling) (x-axis)
• Extend baffling ~7mm (+-0.5mm) inwards from current baffling (y-axis)

The RC14/16 changes are intentionally similar and I’ve verified both to be accurate.

Y-axis: The y-axis numbers above reduce the diameter of the baffling, i.e. the current diameter minus the amount to be corrected is the diameter of the new baffling. The corrected baffling should of course also be centered and not offset from the current baffling.

Material conditions: The baffle shouldn’t move or warp as the telescope changes orientation, shouldn’t warp under changing humidity or temperature, and shouldn’t be reflective.

• Update: There are now also several viewer-made baffle .stl files available on thingiverse (or similar websites) following this video, though I of course can’t personally confirm whether these are accurate.

• Update: There are now various sellers of RC baffles using the designs presented here. I’m sorry, however I also cannot personally vouch for any of these as I have not tested them, nor do I have RC telescopes of various sizes to test them with.