Celestron RASA 8" Rowe-Ackermann Schmidt Astrograph OTA

Celestron 8" RASA Optical Tube Assembly (CGE Dovetail)

Rowe–Ackermann Schmidt Astrograph – Ultra-Fast f/2 Imaging Power

Capture breathtaking wide-field deep-sky images in a fraction of the usual time with the Celestron 8" Rowe–Ackermann Schmidt Astrograph (RASA). Built by Celestron, this portable f/2.0 astrograph is purpose-designed for modern astrophotography, delivering razor-sharp stars across a flat field with remarkably short exposure times.

Weighing just 17 lb (7.7 kg), the RASA 8 is easy to transport to dark-sky locations and pairs beautifully with a wide range of equatorial mounts — making it a powerful yet accessible imaging platform for serious astro-imagers.

Important: The RASA 8 is a dedicated imaging telescope. It is not designed for visual observing — the focal plane is located at the front of the optical system and does not accept eyepieces.

Ultra-Fast f/2.0 Imaging = Shorter Exposures, More Detail

With a blazing-fast f/2.0 focal ratio and 400mm focal length, the RASA 8 dramatically reduces exposure times compared to traditional telescopes. This means:

• Faster acquisition of faint nebulae and galaxies

• Reduced tracking demands on your mount

• In many cases, no autoguiding required

• Ideal for live stacking and near real-time deep-sky viewing

When paired with sensitive CMOS cameras and live-stacking software, you can produce bright, detailed images in seconds rather than minutes.

Flat Field, Sharp Stars — Built Purely for Imaging

The Rowe–Ackermann Schmidt design delivers a fully corrected, flat field with no field curvature, coma, astigmatism, or chromatic aberration across APS-C sensors — producing pinpoint stars edge to edge.

Key optical benefits include:

• Optimised image circle for modern astro cameras

• Outstanding performance from 400–800nm

• Spot sizes under 2.3 μm RMS across the image circle

• Celestron StarBright XLT coatings for maximum light transmission

It offers performance typically associated with much longer focal length systems — without their complexity or cost.

Ultra-Stable Focus System

Celestron’s Ultra-Stable Focus System uses a precision linear ball bearing to virtually eliminate image shift during focusing, slewing, or tracking.

The result:

• More accurate focusing

• Greater repeatability

• Improved stability for long imaging sessions

This is a major advantage when working at f/2, where critical focus is essential.

Designed for Today’s Cameras

The RASA 8 is optimised for:

• Astronomical CMOS cameras

• Smaller CCD cameras

• APS-C mirrorless cameras

It performs best with sensors up to 22mm diagonal, and remains usable up to 32mm with minimal edge degradation.

Full-frame (42mm) sensors will work, but are not fully optimised, with reduced edge performance and illumination.

Not compatible with DSLR cameras.

Included adapters:

• 42mm T-thread camera adapter

• C-thread camera adapter

Mirrorless adapters (Canon / Sony) are sold separately.

Built-In Imaging Conveniences

The RASA 8 includes professional features usually reserved for much larger astrographs:

• Integrated air-cooling system with 12V MagLev fan for rapid thermal stabilisation

• Internal filter mount for light pollution or narrowband imaging filters

• CGE dovetail bar for rock-solid mounting

• Aluminium optical tube for rigidity and thermal stability

All designed to streamline your imaging workflow.

Key Features

• 203mm (8") aperture Rowe–Ackermann Schmidt Astrograph

• Ultra-fast f/2.0 system (400mm focal length)

• Flat, aberration-free field for APS-C sensors

• Ultra-Stable Focus System with precision bearing

• Integrated air cooling

• Internal filter mount

• CGE dovetail mounting rail

• Lightweight 17 lb optical tube

• Optimised for CMOS and mirrorless cameras

Optical Specifications

• Optical Design: Rowe–Ackermann Schmidt Astrograph

• Aperture: 203mm (8")

• Focal Length: 400mm

• Focal Ratio: f/2.0

• Image Circle: 22mm (optimised), usable to 32mm

• Resolution (Dawes): 0.57 arc sec

• Light Gathering Power: 843× human eye

• Wavelength Range: 400–800nm

• Central Obstruction: 46%

• Optical Coatings: StarBright XLT

Physical Specifications

• Optical Tube Length: 628mm

• Optical Tube Diameter: 235mm

• Weight: 17 lb (7.7 kg)

• Focuser: Precision Bearing System

• Dovetail: CGE

• Construction: Aluminium

Included Items

• 42mm T-thread camera adapter

• C-thread camera adapter

• Fan battery pack

• CGE dovetail bar

Why Choose the Celestron 8" RASA?

• Ultra-fast f/2 imaging for dramatically shorter exposure times

• Flat, corrected field for sharp stars across APS-C sensors

• Lightweight and portable for dark-sky travel

• Reduced tracking and guiding requirements

• Designed specifically for modern astro cameras

• Professional-grade features at an accessible size and price

If you’re looking for a powerful, portable deep-sky imaging platform that delivers professional results without the complexity of long focal length systems, the Celestron 8" RASA is an outstanding choice — bringing fast, wide-field astrophotography within easy reach.

Solar safety note: Never observe the Sun without a certified solar filter.