Skywatcher Dobson telescope N 254/1200 Pyrex Skyliner Classic DOB

Sky-Watcher Skyliner Classic 254/1200 Dobsonian Telescope

The Sky-Watcher Skyliner Classic 254/1200 Dobsonian telescope is a powerful and highly efficient optical instrument designed for comprehensive deep-sky exploration. Boasting a massive 254mm (10") aperture, this Newtonian reflector captures an exceptional amount of light to reveal intricate structures in distant galaxies, nebulae, and globular clusters. The straightforward and robust Dobsonian rocker box mount enables instant setup and seamless manual tracking without the complexity of traditional alignment procedures, making it an outstanding choice for both ambitious beginners and dedicated advanced observers.

Key advantages

• Large 254mm (10") aperture delivers high light-gathering capacity for detailed deep-sky observations.
• Pyrex glass primary mirror provides minimal thermal expansion, ensuring excellent image quality even during cooling.
• Diffraction-limited optics with a Strehl Ratio of 0.8 or higher satisfy strict precision criteria.
• Smooth 2" Crayford focuser operates on ball-bearings with zero backlash for precise, shift-free adjustments.
• Tension Control System allows easy tuning of the friction resistance on the wooden rocker box mount.
• Ultra-thin secondary mirror struts reduce diffraction effects and improve contrast.

Product description

Dobsonian telescopes are among the most practical instruments in astronomy. They are of simple construction and yet a brilliant idea. They essentially consist of two parts: firstly the optics, which in most cases is a solid tube design; and secondly the mount, a wooden box (also called a 'rocker box') which sits on the ground and into which the telescope is inserted. This design allows you to begin observing sessions immediately without first having to spend time setting up and aligning a complicated mount. The basic idea of the Dobsonian design came from the wish to have a big telescope at a low price, a wish that has succeeded brilliantly. A true fan base has developed since the invention of the Dobsonian telescope which is dedicated to these instruments and their fascinating simplicity and to the idea of 'high performance at low price'.

The N 254/1200 optics feature a diameter of 254 mm (10") and a focal length of 1200 mm, giving it an aperture ratio of f/4.8. Such optics offer very high light gathering power (1275x). In a reasonably dark sky, you can observe stars down to a magnitude of 14. With an aperture of 254 mm, you can get a lot out of deep sky objects that was not possible with smaller instruments. The secondary mirror struts are very thin and therefore low in diffraction. Due to the diameter of the secondary mirror (58 mm), the obstruction of the optics is 23%.

This telescope has a Pyrex mirror. This type of glass exhibits much smaller thermal expansion than, for example, the commonly used BK7 glass - which is about 2X more than Pyrex. During the cooling phase, the mirror does not warp very much and so keeps its geometric shape much better than a BK7 mirror. So, as a result, the mirror offers better image quality during the cooling phase. Also, Pyrex is easier to figure into a parabola. However, it does not cool down any faster than other mirror materials. The mirror meets at least 75nm p.t.v. or better. So the well-known precision condition Lambda/8 is more than satisfied. The telescopes have a Strehl Ratio of 0.8 or higher. This value expresses something of the optical performance and therefore the quality of the figured surfaces. When theoretically 80% of the light is incorporated in the Airy disk of the telescope image, the optics are described as 'diffraction limited'. That means that the resolution of a telescope is only limited by the diffraction of light. As it is not possible for this to be 100%, the definition of the diffraction limit has been set at 0.8. This always means that you have excellent optics (other systemic losses are not included here).

The 2" focuser is smooth and comes provided with a 1.25" reducer. The finder scope has a fine crosshair, allowing easy location of even the somewhat fainter objects. The Sky-Watcher rocker box is very easy to use. The telescope can be pointed in azimuth and altitude easily and smoothly by using only a couple of fingers. The telescope moves on slide and pivot bearings. It remains stable in any position, allowing highly enjoyable observing. And observing still remains a joy even at higher magnifications. The Tension Control System also lets you easily adjust the friction setting and so the amount of resistance when moving the optics on the rocker box. This allows you to always have the appropriate resistance set.

These instruments are primarily designed for visual observing. Their relatively large apertures mean you can resolve globular clusters and also see some structure in nebulae. Photography of the Moon and Sun are also possible with the appropriate accessories (Sun observation requires an appropriate Sun filter). Photography of other celestial objects requires a mount with tracking capabilities. This mount can be retrofitted later. To be able to get the most out of the instrument, we recommend purchasing at least 2 more eyepieces with 5mm and 14.5mm focal lengths as well as a Barlow lens. Another very useful addition is a UHC-Filter. The telescope also has a 2" Crayford focuser, which runs on ball-bearings and is backlash-free. This is optimal for very accurate, shift-free focusing.

SkyHunters is one of the leading telescope suppliers. Our expert customer service team will gladly help you after your purchase if you have questions or experience any problems with assembly or operation.

Technical specifications

Package contents

• Sky-Watcher Skyliner Classic 254/1200 Telescope (Optical Tube)
• Wooden Rockerbox Mount
• 9x50 Finder scope with fine crosshair
• 12.5mm and 20mm eyepieces (1.25")
• 1.25" & 2" Eyepiece adapter