GSO RC Ritchey-Chretien 6" f/9 M-CRF OTA

The GSO RC OTA presents itself as a specialized optical tube designed specifically for astrophotography. It boasts a real Ritchey-Chretien (RC) system, which is highly esteemed among astronomical telescopes due to its ability to correct coma and astigmatism. Unlike other telescope designs, the RC system utilizes two hyperbolic mirrors that effectively eliminate coma and astigmatism, while also avoiding chromatic aberration by omitting the need for correctors and lenses.

Originally developed by George Ritchey from the United States and Henri Chrétien from France, the RC system was tailored to excel in the field of astrophotography. By eliminating coma, which is a common optical flaw found in most telescopes, the RC system delivers impeccable image quality. Furthermore, the use of hyperbolic mirrors in its construction ensures that the RCT system remains free from chromatic aberrations typically associated with catadioptric systems.

Key Characteristics:

Optimal balance of aperture, quality, weight, and price: The hyperbolic mirror-based optical system of the GSO RC OTA guarantees exceptional image quality, absence of chromatic aberration and coma, high resolution, relatively low weight, all at an affordable price.

Rapid cooling compared to similar telescopes: The open design of RC tubes allows for approximately twice as fast cooling compared to closed tubes such as Maksutov and SCT with the same aperture.

Minimal dew-related issues: Unlike catadioptric tubes and refractor lenses, which are prone to dew settling on the meniscus, the RC tube lacks a meniscus, making condensation on the optics an extremely rare occurrence.

High contrast: The tube's interior is equipped with multiple baffles (diaphragms) and is coated in a non-reflective black material, effectively preventing internal reflections and resulting glare.

Technical Specifications:

• Optical system: Ritchey-Chretien

• Mirror diameter: 150 mm

• Focal length: 1350 mm

• Aperture ratio: f/9

• Tube weight: 5465 g

• Extension weight (including 3 pieces): 535 g

• Optical tube length: 40.5 cm (without extender) / 50.5 cm (with extender)

• Optical tube length with extensions: 60.5 cm / 64 cm (with fully extended max. extender)

• Tube outside diameter (at the front): 18.5 cm

Included Equipment:

• 1 x Vixen standard dovetail, measuring 32.5 cm in length

• Crayford 2"/1.25" dual-speed focuser with a 3.5 cm range and microfocus capability

• Front and back tube caps for protection

• Extenders for the focuser (2 x 2.5 cm optical length, 1 x 5 cm optical length, 77.5 mm diameter)

• Tube finder adapter: Yes, compatible with SkyWatcher/Vixen standard finders.

In summary, the GSO RC OTA offers astrophotographers an exceptional optical system that excels in correcting coma and astigmatism, while avoiding chromatic aberration. With its favorable combination of aperture, quality, weight, and price, along with rapid cooling, minimal dew-related issues, and high contrast, it stands as an attractive option for those seeking superior performance in astrophotography.