Large Aperture Cassegrain Astrograph with 310mm Aperture, 1178mm Focal Length, and F3.8. SHARPSTAR "SCA310" to be Released

SIGHTRON JAPAN CO., LTD. (Head Office: Shinjuku-ku, Tokyo; President: Akira Watanabe) will release the "SCA310," a large aperture Cassegrain astrograph with a 310mm aperture, 1178mm focal length, and F3.8, from the "SHARPSTAR" brand by Jiaxing Ruixing Optical Instrument for astrophotography, on July 3, 2026.

This model features a Cassegrain optical system with an aspheric primary mirror and a spherical secondary mirror made of quartz glass, incorporating a corrector lens with a 3-element, 3-group configuration including one ED glass element. With a wide 55mm image circle and a light-gathering power of 310mm aperture, it is a suitable model for deep-sky photography using large sensors from full-frame to medium format.

*This product is made to order. Please note that delivery will take longer than usual. For details on delivery times, please contact your local dealer.

Product Features

More Efficient Large Aperture Deep-Sky Photography

While large aperture telescopes excel in light-gathering power, their focal lengths tend to be long, requiring long exposure times for faint, extended nebulae. The SCA310 combines the light-gathering power of a 310mm aperture with a bright F3.8 optical system. It incorporates a corrector optical system that supports a 55mm image circle, allowing for wide-field, high-resolution deep-sky photography with large sensors in shorter exposure times.

310mm Light-Gathering Power and F3.8 Brightness

The SCA310 is a large aperture astrograph for deep-sky astrophotography, featuring a bright optical system with a 310mm aperture, 1178mm focal length, and F3.8. It makes it easier to bring out the details and colors of faint nebulae even with short exposures, contributing to improved shooting efficiency.

The primary mirror uses a high-precision aspheric primary mirror. It is designed to effectively suppress spherical aberration and provide sharp star images across the entire field.

The secondary mirror uses a spherical secondary mirror made of quartz glass, which offers excellent thermal stability. Both the primary and secondary mirrors are coated with a highly reflective aluminum coating (reflectivity of 95% or more) to enhance light utilization efficiency.

φ55mm Flat Field Image Circle with Integrated Corrector Optics

The rear of the tube houses a corrector lens with a 3-element, 3-group configuration, including one ED glass element. It is designed to correct for field curvature and various aberrations, providing sharp star images from the center to the periphery.

It ensures a 55mm image circle, fully covering full-frame sensors and also supporting medium format photography. The design maintains nearly 100% of the peripheral light even during full-frame shooting.

Various cameras can be attached using the included M68, M54, and M48 adapters. The M48 adapter has built-in M48 filter threads, making it easy to integrate into your shooting system.

High-Rigidity Mechanism for Easy Handling at the Shooting Site

The tube is made of lightweight and highly rigid carbon fiber material. It minimizes expansion and contraction due to temperature changes, maintaining a stable focus position.

A versatile handle bar for easy carrying is equipped on the top. Multiple slots and screw holes allow for flexible attachment of guide scopes and shooting accessories.

A wide 405mm dovetail bar is equipped at the bottom for stable mounting of the tube. It is compatible with many commercially available equatorial mounts.

Three exhaust fans are built into the rear of the tube. They quickly cool the primary mirror before observation, reducing the time required for thermal acclimatization. Power is supplied via a 12V 0.5A, 5.5mm plug.

A digital thermometer is included.

Large Focuser to Support Large Aperture Shooting

A large, high-rigidity rack and pinion focuser is installed. It features a 30mm focus stroke, allowing for stable operation even when multiple shooting accessories are combined.

The fine focus knob with a reduction gear allows for precise focusing. The front of the focuser has a 360° rotation mechanism, enabling composition adjustment while preventing cable entanglement.

Both the primary and secondary mirrors are equipped with optical axis adjustment screws. Furthermore, since the secondary mirror is a spherical mirror, optical axis adjustment is made easy.

It supports the attachment of various electric focusers, including ZWO's EAF.

Sample Photos

©Zhang Yuhang | IC405 | SCA310 + ZWO ASI461MM Pro

Main Specifications

Aperture

310mm

Focal Length

1178mm

Aperture Ratio

F3.8

Optical System

Cassegrain reflector (aspheric primary mirror, spherical secondary mirror)

Image Circle

φ55mm (Supports medium format, supports full-frame)

Primary/Secondary Mirror Coating

Highly reflective aluminum coating (reflectivity 95% or more)

Corrector Lens

3 elements in 3 groups (1 ED glass element used)

Secondary Mirror Diameter

184mm

Resolution

0.37 arcsec

Tube Material

Carbon Fiber

Tube Outer Diameter

378mm

Total Length

721mm

Weight

23.5kg

Camera Mounting Adapter

M48 (M48x0.75 filter attachable) / M54 / M68

Back Focus

Supports 38-66mm

Focuser

High-rigidity rack and pinion, 30mm stroke, reduction gear

Field Rotation Mechanism

360° rotation at focuser base

Cooling Mechanism

3 exhaust fans built into the rear of the tube (DC12V, 0.5A/5.5mm plug)

Dovetail Bar

405mm wide

Accessories

Thermo-hygrometer, Instruction Manual/Warranty

Release Overview

Brand: SHARPSTAR

Product Name: SCA310

Suggested Retail Price: Open Price

Estimated Market Price: Around ¥1,200,000 (tax included)

Release Date: July 3, 2026 (Fri)

*The estimated market price is solely our company's prediction and may differ from the actual selling price.

*This press release is created based on manufacturer information and provided images. Appearance, specifications, and accessories are subject to change without notice.

*Company names and product names mentioned are trademarks or registered trademarks of their respective companies.

*This product will be handled exclusively by specialized astronomical telescope stores and our directly managed stores.

[Contact Information for This Product]

SIGHTRON JAPAN CO., LTD.

Customer Service Center TEL: 03-6908-3116