Omegon Ritchey-Chretien Pro RC 355/2845 Lightweight Truss OTA (68060)

Omegon Ritchey-Chrétien Pro RC 355/2845 Lightweight Truss OTA (68060)

The Omegon Pro RC 355/2845 is a professional-grade Ritchey-Chrétien reflector designed for advanced astrophotography and observatory use. It combines a large 355 mm aperture with a compact truss-tube structure and precision hyperbolic optics, delivering sharp, coma-free stars across a wide and fully illuminated field.

This system features hyperbolic primary and secondary mirrors, eliminating the need for corrector lenses and significantly reducing optical aberrations. The result is a flat, well-corrected field ideal for large CCD cameras, with approximately 60 mm of illumination suitable for modern imaging sensors.

Quartz Primary Mirror with Honeycomb Structure

The primary mirror is made of high-quality quartz glass and features a lightweight honeycomb structure. This reduces mass and allows the mirror to reach thermal equilibrium more quickly, improving image stability and reducing focus drift. Quartz also provides superior thermal stability compared to standard glass, helping maintain sharp focus throughout long imaging sessions.

Both mirrors are coated with high-reflectivity dielectric coatings rated at 92–94%, delivering brighter, higher-contrast images. Compared to standard 88% reflective coatings, this system reflects significantly more light, enhancing deep-sky performance.

Fast Thermal Adaptation and Active Cooling

The open truss design promotes natural ventilation and prevents heat buildup within the optical tube. Integrated 12V cooling fans accelerate the cooling of the primary mirror, reducing tube seeing and allowing the telescope to reach optimal performance more quickly.

Carbon-Fibre Truss Tube Construction

The carbon-fibre truss structure offers exceptional rigidity with reduced weight and high thermal stability. This design minimizes flexure and focus drift while maintaining structural strength. The open architecture also improves airflow compared to closed-tube systems.

Advanced 3-Inch Linear Crayford Focuser

A bearing-mounted 3-inch linear Crayford (monorail) focuser provides full illumination for large-format cameras without vignetting. The hybrid design combines Crayford smoothness with the stability of a guided rail system, ensuring precise and stable focusing.

Key focuser features include:

• Full 360° rotation for precise framing

• 1:10 fine-focus reduction

• Integrated compression ring on 2-inch to 1.25-inch adapter

• Focus scale for repeatable positioning

• Independent alignment via six collimation screws

Connections include M78x0.75 (female), adapter to M74x0.75 (male), M74 to 2-inch reduction and 2-inch to 1.25-inch reduction.

Advantages Over Schmidt-Cassegrain Systems

Unlike Schmidt-Cassegrain or Maksutov designs, this RC telescope has no corrector plate. The open system adapts more quickly to ambient temperature and avoids internal reflections caused by front plates. With no lenses in the optical path, the telescope avoids chromatic aberration and dispersion, enabling imaging across a broader spectral range, including ultraviolet and infrared wavelengths.

Ritchey-Chrétien systems are widely used in professional research observatories due to their excellent edge-to-edge sharpness and superior correction across the field.

Optical Specifications

Type: Reflector
Design: Ritchey-Chrétien
Aperture: 355 mm
Focal length: 2845 mm
Focal ratio: f/8
Resolving power: 0.32 arcseconds
Limiting magnitude: 15.25
Light-gathering power: 2571x
Maximum useful magnification: 700x
Primary mirror: Hyperbolic quartz, honeycomb structure
Secondary obstruction: 47%
Secondary mirror diameter: 166 mm
Reflectivity: 94%
Coating: Aluminium with silicon dioxide

Tube and Mechanical Details

Tube material: Carbon fibre
Tube construction: Truss tube
Tube diameter: 483 mm
Tube length: 990 mm
Tube weight: 27 kg

Focuser type: Monorail linear Crayford
Eyepiece connection: 3-inch
Fine focusing: 1:10 reduction

Mount type: OTA (no mount included)
GoTo system: No

Included prism rail: Losmandy-style
Extension tubes: Included

Applications

Astrophotography: Yes
Nebulae and galaxies: Yes
Moon and planets: No
Nature observation: No
Solar observation: Not recommended without appropriate solar filter

Recommended For

Beginners: No
Advanced users: Yes
Observatories: Yes

Series: Pro RC