Sky-Watcher Dobson 10" Flex Tube Go-To Telescope (SW-1321)

Sky-Watcher is a global leader in telescope manufacturing, especially known for its Newtonian Dobsonian telescopes. For decades, the company has placed strong emphasis on producing high-quality optics, resulting in excellent views of the Universe and consistently positive reviews from users around the world. With experience dating back to 1990, Sky-Watcher continues to refine its Dobsonian telescopes into elegant, mature, and classic instruments that remain highly economical and accessible. Although many competitors exist, none match Sky-Watcher’s ability to deliver telescopes that combine optical excellence with affordability.

This is a large Newtonian telescope equipped with a 254 mm (10") primary mirror and a 1250 mm focal length. Thanks to its strong optical capabilities, it is an excellent choice for beginners who expect high performance. The 254 mm mirror and fast focal ratio make the telescope well suited for planetary detail as well as deep-sky exploration under dark skies, enabling views of countless star clusters and galaxies.

Go-To System

The telescope includes a Go-To system capable of automatically locating thousands of celestial objects and tracking them across both axes of the Dobsonian base using high-precision stepper motors. Go-To greatly increases observing comfort. Objects can be selected from a menu, and the telescope can be positioned precisely using electronic slow-motion controls. Dual-axis encoders allow manual movement of the telescope without losing alignment or tracking. After selecting a new object, the telescope begins tracking automatically. Control is provided through the included SynScan hand controller or through the built-in Wi-Fi module using the free SynScan Pro app.

A power supply is not included; a mains or battery power source must be purchased separately.

Optical System

The telescope is built in the classic Newtonian design. The parabolic primary mirror has a diameter of 254 mm and a focal length of 1250 mm, giving a focal ratio of f/5. This configuration provides a practical tube length while delivering both low magnifications for faint nebulae and high magnifications for lunar and planetary viewing.

Flex-Tube Collapsible Design

Sky-Watcher’s flex-tube design is unique. Large Dobsonian telescopes can be collapsed for storage, taking up much less space. The structure uses sliding components that require no tools and no disassembly into separate sections. The telescope can be made ready for use within seconds, and the precise mechanism typically eliminates the need for collimation after each setup.

Pyrex Primary Mirror

All Sky-Watcher Dobsonian telescopes 8" and larger come standard with Pyrex mirrors. Pyrex has low thermal expansion, resulting in better optical performance compared with standard glass mirrors.

Mount

The telescope is carried by an alt-azimuth Dobsonian mount—simple, stable, and easy to use. Movements in altitude and azimuth are smooth, and the low center of gravity provides excellent stability compared to equatorial mounts of similar size.

Focuser

The telescope includes a 2" Crayford focuser with a 1.25" adapter. The focuser operates smoothly and without play, and includes a 2" extension tube and a 1.25" extension/adapter (used individually, not combined). It is compatible with Sky-Watcher autofocus motors.

Astronomical Observations

1. Solar System

• Lunar features larger than 1 km

• Sunspots and photospheric granulation

• All planets of the Solar System

• Phases of Mercury and Venus

• Mars with visible polar caps and early surface details

• Several cloud belts on Jupiter, plus Galilean moons

• Saturn’s rings with the Cassini Division, atmospheric bands, and several moons

• Uranus and Neptune as bluish discs

• Motion of minor planets

• Many comets with visible structure

2. Stars

• Around 2.7 million stars visible across the sky down to ~15.5 magnitude

• Double and multiple stars with separations above 0.7–0.8"

• Clear star colors

3. Deep-Sky Objects

• All Messier objects

• Dozens or hundreds of globular clusters, often resolved

• Hundreds of open clusters

• Numerous nebulae with internal structure visible

• Many galaxies showing clear shapes and orientation

• Planetary nebulae showing detailed structure, especially with filters

• Visible supernova remnants

The large 25 cm aperture significantly increases visibility and detail compared to 150 mm or 200 mm telescopes. However, image quality becomes more dependent on sky brightness, air pollution, atmospheric steadiness (seeing), and accurate collimation.

Terrestrial Observations

This optical design is not ideal for daytime use. A correct-image lens is required to produce an upright view. When used with such a lens and placed on the Dobsonian mount, the telescope can serve for basic long-distance terrestrial observations, including watching aircraft at cruising altitude due to the mount’s stiffness and smooth motion.

Safety Notice: When using solar filters with Sky-Watcher Dobson Flex Tube telescopes, a light-blocking shroud must be used. Without it, stray light can enter the tube, risking damage to the filter, telescope, or—most importantly—the observer’s eyesight.

The portable nature of the set means it does not come with a mains power supply. Only a car-adapter power cable is included. A compatible mains power supply is the ESPE 12V/3A adapter.

Included Equipment

• Collapsible Dobsonian mount

• Super Plössl 10 mm and Super Plössl 25 mm eyepieces

• AZ SynScan hand controller

• 9×50 finder

Specification

• Catalog number: SW-1321

• Optical design: Newtonian

• Mount type: Dobsonian

• Aperture: 254 mm

• Focal length: 1250 mm

• Focal ratio: f/4.9

• Limiting magnitude: 14.6

• Maximum useful magnification: 508×

• Resolution (Rayleigh): 0.56"

• Resolution (Dawes): 0.46"

• Light-gathering power: 1317×

• Tube weight: 15 kg

• Mount weight: 27 kg

• Total weight: 42 kg

• Tube length: 800 mm

• Tube diameter: 290 mm

• Tripod type: Dobsonian

• Tripod height: 740 mm

• Mount control: SynScan Go-To

• Focuser type: Crayford

• Focuser size: 2"

• Focuser micromotion: No

• Secondary mirror diameter: 58 mm

• Electronics warranty: 24 months

• Overall warranty: 60 months