The Orion SkyQuest XX12g is a 12-inch (305mm) GoTo Dobsonian telescope built around a collapsible truss-tube optical assembly. Its large aperture gives it substantially greater light-gathering ability than the smaller telescopes we’ve been reviewing, making faint deep-sky objects one of its particular strengths.
The XX12g also combines the traditional Dobsonian format with motorized GoTo object locating and tracking. Once the system has been aligned, the hand controller can direct the telescope toward objects in its database and the motors can then track them as they move across the sky.
This is a large and heavy telescope despite its collapsible design. The truss system makes transportation more practical than it would be with an equivalent solid optical tube, but the XX12g is better regarded as a large telescope that can be broken down for transport than as an easily portable instrument.
305mm f/4.9 Reflector Optics
The SkyQuest XX12g uses a 305mm (12-inch) parabolic primary mirror with a 1500mm focal length, producing a focal ratio of f/4.9. The large aperture is the telescope’s most important optical characteristic, collecting considerably more light than smaller amateur telescopes.
That light-gathering ability is particularly valuable for observing galaxies, nebulae, globular clusters and other relatively faint deep-sky objects. Under dark skies, a 12-inch aperture can reveal structure and detail in objects that appear much fainter or less developed through smaller instruments.
The telescope uses a dual-speed 11:1 Crayford focuser accepting both 2-inch and 1.25-inch eyepieces. The fine-focus control is particularly useful when making small focusing adjustments at higher magnifications.
As with other relatively fast Newtonian reflectors, accurate collimation is important for obtaining the best optical performance, while coma can become apparent toward the edge of wide fields.
GoTo Object Finding and Tracking
The XX12g differs from a traditional manual Dobsonian by incorporating motorized GoTo and tracking on both the altitude and azimuth axes.
After completing the required alignment procedure, the observer can select an object using the hand controller and the telescope will slew toward its calculated position. Once an object has been located, the motors can track it as Earth rotates, reducing the need to continually reposition the telescope by hand.
The telescope can also be moved manually. Its clutch and encoder system allows the optical tube to be repositioned by hand without necessarily losing the GoTo alignment, combining some of the direct movement of a conventional Dobsonian with computerized assistance.
What Can You See Through the SkyQuest XX12g?
The XX12g’s 12-inch aperture makes deep-sky observing one of its strongest roles. Bright nebulae such as the Orion Nebula can show extensive structure, while globular clusters can begin to resolve into large numbers of individual stars under suitable conditions.
Many galaxies that appear as faint smudges through smaller telescopes become easier to detect, and brighter examples can reveal considerably more structure from a dark observing site. Planetary nebulae and smaller deep-sky objects also benefit from the combination of aperture and useful magnification.
The large aperture is equally useful on the Moon and planets. Lunar craters and fine surface features can be observed at high magnification, while Jupiter’s cloud belts and Galilean moons and Saturn’s rings are prominent targets. When atmospheric seeing is sufficiently steady, the aperture can support detailed planetary observations.
As always, what is actually visible depends heavily on sky darkness, atmospheric conditions, the target’s position and the observer’s experience.
Truss-Tube Design and Transport
A solid-tube 12-inch Dobsonian is a physically large instrument, so the XX12g uses a truss-tube design that allows the optical assembly to be separated into smaller components for transportation and storage.
This makes the telescope more manageable than an equivalent permanently assembled tube, but it does not make it lightweight. Orion specified the assembled optical tube at approximately 47 lb (21.3 kg) and the base at approximately 89 lb (40.4 kg).
The telescope therefore requires considerably more planning to move and set up than a small refractor, Maksutov or tabletop Dobsonian. Observers who regularly transport it to dark-sky sites need enough vehicle space for its components and must be comfortable handling substantial pieces of equipment.
Reassembling the truss structure also means that collimation should be checked during setup to ensure the mirrors remain correctly aligned.
Limitations to Consider
The XX12g’s greatest practical limitation is its size and weight. Although the truss-tube design makes transportation possible, the 89 lb base in particular is a substantial component to move. This telescope is therefore poorly suited to anyone wanting a genuinely grab-and-go observing setup.
The GoTo system also adds complexity compared with a traditional manual Dobsonian. It requires electrical power and an alignment procedure before computerized object locating and tracking can be used.
Like other Newtonian reflectors, the XX12g requires periodic collimation, and its relatively fast f/4.9 optics can show coma toward the edge of wide fields. The open truss section can also admit stray light, making a light shroud useful under some observing conditions.
Finally, the XX12g is a discontinued Orion model. Anyone encountering one today should therefore consider the condition and completeness of the telescope, particularly its electronic GoTo components and hand controller.
Who Is the SkyQuest XX12g Best For?
The SkyQuest XX12g is best suited to observers who want large-aperture visual performance for deep-sky observing together with computerized object finding and tracking. Its 12-inch mirror also provides excellent potential for lunar and planetary observing, but its considerable size and weight make it a better fit for someone prepared to manage a substantial observing setup rather than an observer prioritizing portability.
Specifications
- Optical Design: Newtonian reflector
- Primary Mirror: 305mm (12 inches), parabolic
- Focal Length: 1500mm
- Focal Ratio: f/4.9
- Optical Tube: Truss-tube design
- Focuser: Dual-speed 11:1 Crayford
- Eyepiece Compatibility: 2-inch and 1.25-inch
- Mount: Motorized altitude-azimuth Dobsonian
- Object Locating: GoTo
- Tracking: Motorized
- Finder: EZ Finder II reflex sight
- Original Supplied Eyepieces: 28mm 2-inch DeepView and 12.5mm illuminated Plössl
- Optical Tube Weight: approximately 47 lb (21.3 kg)
- Base Weight: approximately 89 lb (40.4 kg)
- Power Requirement: 12V DC, 2.1A