Sharpstar SCA260 V2 Aspherical Cassegrain Astrograph

Developed for high-resolution astrophotography, the Sharpstar SCA260 V2 combines a 260 mm aperture, a 1300 mm focal length and a fast f/5 focal ratio. Its aspherical Cassegrain system integrates an optical corrector suitable for full-frame sensors.

Optimised optical design

Optical architecture based on an aspherical primary mirror and a spherical secondary mirror. Manufacturing, machining and testing an aspherical mirror require more sophisticated processes than those used for a conventional reflecting mirror.

Primary mirror manufactured from PZ33 glass, a material with properties similar to Pyrex glass. This composition contributes to the stability of the optical system during temperature changes.

Carbon-fibre optical tube combines rigidity, durability and controlled weight. Its outside diameter is 304 mm, with an announced tube weight of 14.5 kg.

High-reflectivity mirrors

Primary and secondary mirrors feature enhanced aluminium coatings providing reflectivity above 95%.

A simplified optical-axis adjustment system facilitates collimation. Adjustment is performed through the secondary-mirror adjustment rods.

3-inch optical corrector

Large-diameter corrector integrated into the optical path and composed of three air-spaced elements. This design corrects the photographic field and provides an 80 mm image circle.

Full-frame sensors are supported with field correction designed for astronomical imaging while limiting vignetting around the edges.

Multifunctional carrying handle

Upper handle CNC-machined from a solid aluminium block and featuring an open structure. Its design contributes to mechanical rigidity while reducing unnecessary weight.

This handle can also be used as a mounting base for additional accessories.

Improved 3.35-inch focuser

Dedicated 3.35-inch focuser offering 50 mm of focusing travel. This extended range helps accommodate different photographic configurations.

Improved load capacity supports imaging cameras and accessories without slipping while maintaining smooth and precise movement.

Integrated rotator and versatile connections

Rear rotator allows the sensor to be oriented through 360 degrees. This function simplifies photographic framing and reduces the risk of a focusing-motor cable becoming tangled during rotation.

Three threaded interfaces are available for different imaging configurations:

• M68 × 1
• M54 × 0.75
• M48 × 0.75

An integrated 2-inch filter thread provides an additional connection option.

Distance between the M48 interface face and the focal plane is 70 mm.

Technical specifications

• Type: aspherical Cassegrain astrograph
• Model: SCA260 V2
• Aperture: 260 mm
• Focal length: 1300 mm
• Focal ratio: f/5
• Primary mirror: aspherical reflecting mirror
• Primary-mirror material: PZ33 glass similar to Pyrex
• Secondary mirror: spherical reflecting mirror
• Secondary-mirror minor axis: 120 mm
• Mirror coating: enhanced aluminium
• Reflectivity: above 95%
• Corrector: three air-spaced elements
• Corrector diameter: 3 inches
• Image circle: 80 mm
• Tube material: carbon fibre
• Tube diameter: 304 mm
• Tube weight: 14.5 kg
• Announced resolution: 0.46 arcsecond
• Announced limiting visual magnitude: 13.8
• Focuser: 3.35 inches
• Focuser travel: 50 mm
• Rotator: 360 degrees
• Interfaces: M68 × 1, M54 × 0.75 and M48 × 0.75
• Filter thread: 2 inches
• Distance from M48 face to focal plane: 70 mm
• Handle: CNC-machined aluminium with accessory support