Sharpstar SCA310 f/3.8 Aspherical Cassegrain Astrograph

310mm f/3.8 Aspherical Optics: A 55mm Corrected Image Circle

At the core of the SCA310 is a 310mm aspherical primary mirror, precisely figured to eliminate spherical aberration for sharp, point-like stars. Paired with a thermally stable secondary, this system achieves a 1178mm focal length. A permanently integrated 3-element corrector, featuring one ED glass element, flattens the field and corrects for coma, producing a 55mm image circle capable of covering the largest full-frame and medium-format CMOS sensors with near 100% illumination.

721mm Carbon Fiber Tube: Thermal Stability at 23.5kg

The SCA310's optical path is housed in a carbon fiber tube, which offers a superior stiffness-to-weight ratio and minimal thermal expansion. This ensures that focus remains stable during temperature drops over a long imaging session. The entire optical tube assembly is only 721mm long, a significant advantage for portability and mount requirements compared to other designs of similar aperture, and weighs a substantial 23.5kg.

3.5-inch Focuser: 30mm Travel and 360° Rotation

To handle modern heavy imaging trains, the SCA310 is equipped with a 3.5-inch high-rigidity rack-and-pinion focuser. This unit provides 30mm of travel with a 1:10 dual-speed knob for precise adjustments and can support heavy camera and filter wheel combinations without slippage. A 360° rotator allows for easy framing of your target, and the rear is equipped with M68, M54, and M48 adapters for direct connection to your camera. The M48 adapter also includes a built-in thread for 2-inch filters.

Integrated Cooling: 3 Fans for Rapid Thermal Equilibrium

To maximize image quality from the start of your session, the SCA310 integrates three cooling fans behind the primary mirror. Activating these fans before you begin imaging rapidly brings the 310mm primary mirror to ambient temperature. This minimizes tube currents and ensures the sharpest possible views, significantly improving efficiency and overall imaging results.

SCA310 vs. 12" Newtonian Astrographs: The Cassegrain Advantage

While a 12" (approx. 300mm) f/4 Newtonian offers similar aperture and speed, the SCA310's Cassegrain design provides distinct advantages for the dedicated astrophotographer.

• Compactness: The SCA310's 721mm tube is over 400mm shorter than a typical 12" f/4 Newtonian OTA. This makes it easier to transport, balance, and house in an observatory, and it places less strain on the mount.
• Integrated Correction: The SCA310's corrector is a permanent, optimized part of the optical design. You do not need to purchase or install a separate coma corrector, and the back focus is fixed and simple to work with.
• Stray Light and Dew: The closed carbon fiber tube offers superior protection against stray light and dew formation compared to the open-truss or single-wall design of most large Newtonians.