GSO DO-GSO Dobson 12" F/5 M-CRF Telescope (GS980)

The GSO DO-GSO Dobson 12" F/5 M-CRF (GS980) is a large Newtonian telescope created for both beginner and advanced astronomy enthusiasts who expect high-quality performance. It is excellent for visual observations, delivering bright, sharp, and clear images. Under dark, rural skies, this telescope can reveal almost all astronomical objects, limited only by sky quality and atmospheric conditions. Despite its size, it can fit into most larger cars, making it practical for transport.

Optical Tube:
The tube is constructed using the classic Newtonian design from rigid rolled steel. The interior is well-blackened to reduce reflections and improve contrast, especially when observing bright objects like the Moon and planets.

Optical System:
The primary mirror is parabolic, made from high-quality BK7 glass, with a diameter of 304 mm, focal ratio of f/5, and a focal length of 1500 mm. It is mounted in a sturdy cell with three support points. The secondary mirror is held by a thin, durable spider, reducing image artifacts. Enhanced aluminum coatings provide about 93% reflectivity.

Mount:
The Dobsonian mount is simple to set up and does not require alignment with the celestial pole. It is a stable, box-type construction capable of supporting heavy telescopes. The mount allows smooth movement in both azimuth and altitude, thanks to roller bearings and a low center of gravity. The telescope is held in a fork mount with two metal pivots, each with a locking knob. The mount also features a tube balancing system for different eyepiece weights.

Focuser:
This model features a high-quality Crayford focuser made from CNC-machined aluminum. It operates smoothly and precisely, with four bearings and a roller, and has no play. The focuser includes a 10:1 micro-adjustment for fine focusing, two large adjustment screws (one for locking, one for tension), and supports both 1.25" and 2" eyepieces with an included adapter. It can hold accessories up to about 3 kg.

Cooling:
A fan is installed under the primary mirror to improve air circulation and speed up cooling. The fan is powered by an included 8xAA battery holder.

Terrestrial Observations:
This telescope is not ideal for terrestrial viewing as the image is inverted. With an erecting lens and the included mount, it can be used for basic terrestrial observation, such as viewing airplanes at cruising altitude.

Astronomical Observations:

• Solar System: Surface features on the Moon as small as 3 km, all planets, Mercury and Venus phases, Mars’ polar caps and surface details, Jupiter’s bands and Galilean moons, Saturn’s rings and Cassini Division, Uranus and Neptune as blue disks, asteroid movement, and faint comets

• Stars: Stars down to about magnitude 16, double and multiple stars

• Nebulae: All Messier and NGC catalog objects

With its 30 cm mirror, the telescope reveals much more detail than smaller models, but is more sensitive to light pollution, air quality, and atmospheric stability. Proper optical collimation is important for the best results.

Included Accessories:

• 35mm extension tube

• 1.25" 9 mm eyepiece

• 2" 30 mm eyepiece

• 8x50 straight finderscope

• Cooling fan with battery holder

Specifications:
Catalog Number: GS980
Optical Design: Newtonian
Mount Type: Dobsonian
Aperture: 304 mm
Focal Length: 1500 mm
Focal Ratio: f/4.9
Limiting Magnitude: 15.0
Maximum Useful Magnification: 608x
Maximum Resolution (Rayleigh): 0.47"
Maximum Resolution (Dawes): 0.38"
Light Gathering Power: 1886x
Tube Weight: 19.5 kg
Mount Weight: 13.5 kg
Total Weight: 33 kg
Tube Length: 1450 mm
Tube Diameter: 365 mm
Mount Height: 64 cm
Mount Control: Manual
Focuser Type: Crayford
Focuser Size: 2"
Focuser Micro-adjustment: Yes
Secondary Mirror Diameter: 70 mm
Central Obstruction: 25%
Coatings: Aluminum with SiO4 coating
Warranty: 24 months