Sky-Watcher Dobson 12" Flex Tube 305/1500 Telescope (SW-1312)

Sky-Watcher is a global leader in the production of astronomical telescopes, particularly Newtonian telescopes mounted on Dobsonian bases. Since 1990, the company has focused on manufacturing premium-quality optics, earning an outstanding reputation among amateur and professional astronomers worldwide. Sky-Watcher Dobson telescopes are known for combining excellent optical performance, elegant classic design, reliability, and outstanding value for money. Although many manufacturers offer similar designs, Sky-Watcher remains one of the industry's leading names for affordable, high-performance Dobsonian telescopes.

This model is a large Newtonian reflector featuring a 305 mm (12-inch) primary mirror with a 1500 mm focal length. Its impressive light-gathering capability makes it an excellent choice for both ambitious beginners and experienced observers. The large aperture provides outstanding views of the Moon and planets while revealing hundreds of deep-sky objects such as galaxies, nebulae, and star clusters under dark skies. Many fine details invisible in smaller telescopes become clearly visible with this aperture.

Optical System

The telescope features a classic Newtonian optical design with a parabolic primary mirror measuring 305 mm (12 inches) in diameter and a 1500 mm focal length. With a focal ratio of f/4.9, it offers an excellent balance between light-gathering power and portability.

Its moderate focal length allows comfortable low-power observations of faint deep-sky objects while also supporting high magnifications for detailed observations of the Moon and planets.

Flex Tube Collapsible Design

Sky-Watcher's Flex Tube design is unique among large Dobsonian telescopes. The optical tube can be collapsed for storage and transportation, significantly reducing its size without requiring complete disassembly.

The extension mechanism operates quickly and requires no tools. Within seconds, the telescope can be fully extended and ready for observation. The precision-engineered design ensures that collimation typically remains stable after extending the tube.

Pyrex Primary Mirror

All Sky-Watcher Dobson telescopes with apertures of 8 inches (200 mm) or larger are equipped with Pyrex mirrors as standard.

Pyrex glass has very low thermal expansion, allowing the mirror to reach thermal equilibrium more quickly while maintaining superior optical performance compared to standard glass mirrors.

Dobsonian Mount

The telescope is mounted on a sturdy alt-azimuth Dobsonian mount that provides exceptionally stable support and smooth movement along both the altitude and azimuth axes.

The tube is held securely within a dual-sided fork mount while the base rotates smoothly. Thanks to its low center of gravity and rigid construction, the Dobsonian mount offers excellent stability and minimal vibration, often outperforming comparable equatorial mounts in this regard.

Focuser

The telescope includes a 2-inch Crayford focuser with a 1.25-inch adapter.

The Crayford design provides smooth, backlash-free focusing. The package includes:

• 2-inch extension tube

• 1.25-inch adapter/extension

These accessories should be used individually rather than combined together.

The focuser is also compatible with Sky-Watcher electronic autofocuser systems.

Astronomical Observing Performance

Solar System

This telescope is capable of observing:

• Lunar surface features smaller than 1 km under favorable conditions

• Sunspots and detailed solar photosphere granulation (only with a proper certified solar filter)

• All planets of the Solar System

• Phases of Mercury and Venus

• Polar caps and surface markings on Mars during opposition

• Multiple cloud bands and the Galilean moons of Jupiter

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

• Uranus and Neptune as distinctly bluish planetary disks

• Motion of numerous asteroids against the background stars

• Many faint comets, including visible coma structure

Stars

The telescope can reveal:

• Approximately 2.7 million stars across the sky down to about magnitude 15

• Double and multiple stars separated by more than approximately 0.6 arcseconds

• Rich color differences among many stars

Deep-Sky Objects

The telescope allows observation of:

• Every object in the Messier Catalogue

• Dozens to hundreds of globular clusters, many fully resolved into individual stars

• Hundreds of open star clusters with clearly visible structural differences

• Numerous emission and reflection nebulae showing fine internal detail

• Many galaxies with recognizable shapes, orientations, and structural features

• Planetary nebulae with improved contrast when using nebula filters

• Supernova remnants

With its large 305 mm aperture, celestial objects appear significantly brighter and more detailed than in 150 mm or 200 mm telescopes. However, larger apertures are also more sensitive to light pollution, atmospheric turbulence (seeing), air quality, and precise optical collimation. These factors should be considered to achieve the best possible observing performance.

Terrestrial Observations

Like most Newtonian reflectors, this telescope is not ideally suited for terrestrial viewing because it produces an inverted image.

A correct-image erecting lens can be used to obtain an upright view, making the telescope suitable for basic daytime observations. Thanks to the smooth and rigid Dobsonian mount, it is also capable of tracking aircraft and distant terrestrial targets with ease.

Important Safety Warning

When using certified solar filters with Sky-Watcher Dobson Flex Tube telescopes, a light shroud must always be installed to prevent stray sunlight from entering through the open tube sections.

Failure to use a light shroud may damage the solar filter, the telescope, or, most importantly, result in permanent eye injury. Always follow proper solar observing safety procedures.

Included Accessories

• Super Plössl 25 mm (1.25") eyepiece

• Super Plössl 10 mm (1.25") eyepiece

• 9×50 optical finder scope

Technical Specifications

• Catalog Number: SW-1312

• Telescope Series: Sky-Watcher Dobson Flex Tube

• Optical Design: Newtonian Reflector

• Mount Type: Dobsonian Alt-Azimuth

• Aperture: 305 mm (12")

• Focal Length: 1500 mm

• Focal Ratio: f/4.9

• Limiting Stellar Magnitude: 15.0

• Maximum Useful Magnification: 610×

• Rayleigh Resolution: 0.47 arcseconds

• Dawes Resolution: 0.38 arcseconds

• Light Gathering Power: 1,898× (compared to the human eye)

• Optical Tube Weight: 21 kg

• Mount Weight: 19 kg

• Total Weight: 40 kg

• Tube Length: 1400 mm

• Tripod/Base Type: Dobsonian Base

• Base Height: 740 mm

• Mount Control: Manual

• Focuser Type: 2" Crayford

• Focuser Diameter: 2"

• Fine Focus Reduction: No

• Secondary Mirror Diameter: 70 mm

• Warranty: 60 months