SkyWatcher Skyliner 250px Flex-Tube Dobsonian Enhanced 10157

You cannot really beat a big, light-gulping  Dobsonian for visual astronomy. The only drawback is the bigger they get, the more unwieldy they become to carry, transport and store. Traditional truss tube designs require assembly which is time-consuming. Sky-Watcher’s clever, patent-protected FlexTube™ collapsible truss tube design is a true game-changer that requires no assembly. The OTA can be easily retracted or extended in seconds on three extremely rigid poles. There is no lateral movement or flexure when extended and the telescope maintains its collimation. There is a separate, slightly shorter locking position should a binoviewer be used. In its collapsed form it can be carried and neatly stored in the vertical position. The OTA can also be easily separated from the base by unscrewing the tension handles, making transportation much easier.

The Sky-Watcher Skyliner 250P Flextube Dobsonian, with its stunning parabolic optics, provides excellent all-round performance and will deliver truly memorable views of the Moon & Planets and Deep Sky Objects such as Galaxies, Nebulae & Star Clusters. Skyliner Flextube Dobsonians are popular telescopes with beginners and experienced users alike. Due to their high performance and simple reliable operation and are often the only telescope some users will ever need. Although we at Sky-Watcher love computerised telescopes, using a star chart to find objects by hand can be far more fulfilling and will improve your knowledge of the night sky. Unplug your electronic devices, step outside, and become immersed in the wonders of the universe. It is a profoundly rewarding experience to view the treasures of the night sky through an eyepiece, in real time.

Often referred to as ‘Light Buckets’, traditional Dobsonian telescopes provide users with the highest possible aperture for their money when compared to other telescopes of a similar size, offering an incredible aperture-to-price ratio, because most of its cost goes towards the optical tube. The Dobsonian mount, popularized by John Dobson in the 1970s, is a simple and efficient method of mounting a Newtonian reflector, based on the Alt-Azimuth principal. Fast & easy to set up with no time-consuming alignments, the Dobsonian mount consists of a rocker box-type mounting which allows the telescope to pivot in altitude, while the box itself is rotated on a base in azimuth. The secret of the design is to correctly balance the optical tube and use low-friction materials which allow it to be moved easily when nudged but to stay in position when not. The mount is designed to be driven by hand as opposed to slow motion controls or by a motor.

The heart of any Dobsonian telescope is in the quality of its mirror optics. The accuracy of the figure, the material they are made from and the coatings applied all play an important part towards the telescope’s performance. Sky-Watcher’s prowess and reputation for commercial mirror making is well known and one of the jewels in its crown. Sky-Watcher are experts in this field and has demonstrated its unwavering ability to produce telescope mirrors of consistent high quality over decades. Parabolic (or Paraboloidal) mirrors are a complex shape so need to be well made to provide the high performance expected of them. A properly figured parabolic primary mirror will eliminate spherical aberrations by bringing the light rays to the same focal point. Sky-Watcher’s diffraction-limited parabolic primary mirrors will produce sharp, contrasty images that are full of detail.

The Skyliner Flextube 250P primary & secondary mirrors are made from special Low-Expansion Borosilicate glass, similar to Pyrex, which has an exceptionally low coefficient of thermal expansion compared to regular glass types. In practice this means a quicker cool-down time to reach thermal equilibrium, without the reliance on a cooling fan, and during the cool-down process the mirrors will maintain a better shape, reducing distortions, allowing you to start observing sooner.

Both primary and secondary mirrors are finished with Sky-Watcher’s RAQ™ Radiant Aluminium Quartz coatings, which include layers of aluminium, tantalum pentoxide (dielectric) and silicon dioxide for a brilliant, highly durable finish with 94% reflectivity that will last for years.

The secondary mirror is held in place by four specially designed 0.5mm thin spider vane supports which are extremely rigid when tensioned. They serve to minimise obstruction to the light path, allowing the passage of more precious photons and keeping diffraction spikes to an absolute minimum.

Supporting the Skyliner Flextube Dobsonian is more than just a simple rocker box. The base uses special low-friction bearings for smooth, easy azimuth slewing and cleverly designed patent-protected tension control handles which ensure you always have the appropriate level of resistance for precise slewing and maximum stability. Just the right amount of tension can be intuitively applied in seconds in order to maintain perfect balance when heavy eyepieces are used, or even fully lock the vertical axis. They also conveniently double as carrying handles.  An accessory tray is included to keep your accessories safe in one place. The telescope OTA can be quickly and easily separated from the base unit for convenient transportation.

The colour scheme is not just an aesthetic. Skyliner FlexTube Dobsonians are beautifully finished in Sky-Watcher’s proprietary Black Diamond flecked metallic paintwork and features, by design, complementary contrasting white surfaces. The white surfaces are a highly practical feature for providing more visibility, which can help prevent your expensive and carefully aligned telescope from being knocked accidentally in the dark

PARABOLIC PRIMARY MIRRORS
Features High Quality Parabolic Primary Mirrors to eliminate spherical aberrations inherent in ‘fast’ focal lengh reflectors with spherical primary mirrors. The mirrors are parabolized to bring all the light rays to the same focal point to give sharp, constrasty images, which are full of detail. SKY-WATCHER DELUXE MIRROR COATINGS
Most reflectors today usually have a coat of aluminium as the mirror surface and then an overcoat of silicon monoxide or silicon dioxide to protect it. Silicon dioxide produces a much more durable coat than silicon monoxide but requires specialized equipment to apply it and is therefore more expensive. Protection is needed, because in most reflectors, the mirror is open to the elements and deterioration of the reflective layer reduces the resolution of the telescope.ALL Sky-Watcher reflectors are Multi-Coated with Silicon Dioxide as standard for Optimum Durability and Long Term Performance.