Sky-Watcher Skyliner-250PX FlexTube 10" Dobsonian Telescope

Sky-Watcher Skyliner 250P FlexTube 10-Inch Dobsonian Telescope

The Sky-Watcher Skyliner 250P FlexTube combines powerful 254mm parabolic optics with an ingenious collapsible optical tube. This makes it easier to store and transport than a traditional solid-tube telescope of comparable aperture, without requiring the time-consuming assembly associated with conventional truss-tube designs.

Its large 10-inch primary mirror delivers outstanding visual performance across the Moon, planets and deep-sky objects. This enhanced edition also includes two 70° super-wide-angle eyepieces, a comfortable 90° angled finderscope and a universal smartphone adaptor.

Product code: 10157
Brand: Sky-Watcher

Key Features

• Large 254mm parabolic primary mirror

• 56% more light-gathering ability than a 200mm telescope

• Collapsible FlexTube design for easier storage and transportation

• Low-expansion borosilicate mirror glass for improved thermal stability

• Excellent lunar, planetary and deep-sky performance

• Simple manual Dobsonian mount with smooth movement

• 2-inch precision Crayford focuser

• Compatible with 1.25-inch and 2-inch eyepieces

• 12.5mm and 20mm 70° super-wide-angle eyepieces included

• 90° angled 9x50 erect-image finderscope

• Universal smartphone camera adaptor included

• RAQ™ mirror coatings offering up to 94% reflectivity

• Additional tube position for use with a binoviewer

What Can You See?

The generous 254mm aperture gathers considerably more light than a smaller beginner telescope, revealing fainter objects and finer details under suitable observing conditions.

Possible targets include:

• Detailed lunar craters, valleys, mountain ranges and rilles

• Jupiter’s cloud bands, Galilean moons and Great Red Spot

• Saturn’s rings and the Cassini Division

• The phases of Venus

• Martian surface features and polar regions when favourably positioned

• Bright nebulae such as the Orion Nebula

• Planetary nebulae, including the Ring Nebula

• Open and globular star clusters

• The Andromeda Galaxy and numerous other galaxies

• Double stars and many objects from the Messier and NGC catalogues

Its combination of a large aperture and 1200mm focal length makes the Skyliner 250P particularly impressive for deep-sky exploration while remaining highly capable for lunar and planetary observing.

Collapsible FlexTube Design

Large-aperture Dobsonian telescopes provide spectacular views, but conventional solid optical tubes can become difficult to carry, transport and store.

Sky-Watcher’s patented FlexTube collapsible system provides an intelligent solution. The upper section of the optical tube extends and retracts along three rigid supporting poles, allowing the telescope to be prepared for use or collapsed for storage in seconds.

Unlike a traditional truss-tube telescope, there are no separate poles or components to assemble. Once extended and locked, the structure is designed to remain rigid and maintain the telescope’s collimation.

The FlexTube system also includes a separate, slightly shorter locking position for observers using a compatible binoviewer.

When collapsed, the optical tube measures approximately 800mm long and can be stored vertically to conserve space. It can also be separated from the base by releasing the tension-control handles, making transportation more manageable.

Powerful Visual Astronomy

Dobsonian telescopes are frequently described as “light buckets” because they offer a large light-gathering aperture without the expense of a complex computerised mount.

The Skyliner 250P places the emphasis firmly on optical performance. Its 254mm primary mirror gathers approximately 56% more light than a 200mm telescope, helping to reveal fainter deep-sky objects and additional detail within brighter targets.

This exceptional aperture-to-price ratio makes the Skyliner 250P an excellent choice for observers who want serious visual performance from a straightforward manual telescope.

Simple Manual Operation

The Skyliner 250P uses a traditional manual Dobsonian mount. There are no electronics, motors or complicated alignment routines to configure. Place the telescope on a suitable level surface, extend the optical tube, insert an eyepiece and guide it towards your chosen target by hand.

Smooth movement in altitude and azimuth allows the telescope to be gently directed around the sky. Objects can be found using a star chart or astronomy app and followed by occasionally nudging the optical tube as they move across the field of view.

This simple and dependable design makes the Skyliner 250P suitable for enthusiastic beginners while offering enough optical performance to satisfy experienced observers for many years.

High-Quality Parabolic Optics

At the heart of the Skyliner 250P is a carefully figured, diffraction-limited parabolic primary mirror.

The parabolic shape brings incoming light rays to the same focal point, helping to eliminate the spherical aberration associated with basic spherical mirrors. This produces sharp, high-contrast views filled with fine detail.

The primary and secondary mirrors are manufactured from low-expansion borosilicate glass, similar to Pyrex. This specialist material is less affected by changing temperatures than conventional glass, helping the mirrors maintain their intended shape while cooling.

This improved thermal stability reduces temporary optical distortions and helps the telescope reach thermal equilibrium more quickly, allowing clearer observing to begin sooner.

Durable RAQ™ Mirror Coatings

Both mirrors feature Sky-Watcher’s RAQ™ Radiant Aluminium Quartz coatings.

These multilayer coatings combine aluminium with dielectric tantalum pentoxide and protective silicon dioxide. They offer reflectivity of up to 94%, helping more of the collected light reach the eyepiece while providing a durable finish designed for long-term performance.

The secondary mirror is supported by four rigid 0.5mm ultra-thin spider vanes. Their slender profile minimises obstruction within the light path and helps keep diffraction effects to a minimum.

Smooth and Stable Dobsonian Base

The wooden alt-azimuth base uses low-friction bearings to deliver smooth, controlled movement. The telescope can be guided with a gentle push while remaining stable when released.

Sky-Watcher’s adjustable tension-control handles allow the resistance of the altitude movement to be altered in seconds. This helps maintain the telescope’s balance when changing between eyepieces of different weights or adding accessories.

The vertical axis can also be locked when required, while the tension handles double as convenient carrying points. An integrated accessory tray keeps eyepieces and other small accessories close at hand during observing sessions.

Enhanced Accessory Package

This enhanced edition includes several useful upgrades over the standard factory configuration.

The supplied 90° angled 9x50 erect-image finderscope provides a more comfortable observing position than a conventional straight-through finder. Its correctly orientated view also makes it easier to compare visible star patterns with a printed star chart.

Two 70° super-wide-angle eyepieces are included:

• 20mm eyepiece: Provides 60x magnification for locating targets and enjoying wider views

• 12.5mm eyepiece: Provides 96x magnification for closer observation of the Moon, planets and smaller deep-sky targets

Their wide apparent field of view provides a more immersive experience and gives objects more time to drift across the view before the telescope needs to be repositioned.

Smartphone Astrophotography

A universal smartphone adaptor is included, allowing compatible phones between 54mm and 90mm wide to be positioned over the eyepiece.

This provides an accessible introduction to smartphone astrophotography and is particularly suitable for capturing images or short videos of bright subjects such as the Moon and, with patience, some of the brighter planets.

The telescope also supports a direct SLR camera connection. However, its manual Dobsonian mount is primarily designed for visual observation and is not suitable for conventional long-exposure deep-sky astrophotography.

Precision Crayford Focuser

The Skyliner 250P features a smooth 2-inch precision Crayford focuser supplied with adaptors for both 2-inch and 1.25-inch eyepieces.

The 1.25-inch adaptor uses a brass compression ring to secure eyepieces without marking their barrels. Compatibility with both popular eyepiece sizes also provides plenty of options for expanding your accessory collection in the future.

Practical Night-Time Finish

The optical tube is finished in Sky-Watcher’s distinctive Black Diamond flecked metallic paintwork, complemented by contrasting white sections.

The white surfaces are not purely decorative. They improve the telescope’s visibility in dark observing environments, reducing the risk of accidentally walking into or knocking the equipment at night.

What’s Included?

• Sky-Watcher Skyliner 250P FlexTube optical tube assembly

• Wooden Dobsonian alt-azimuth base

• 20mm 70° super-wide-angle eyepiece

• 12.5mm 70° super-wide-angle eyepiece

• 90° angled 9x50 erect-image finderscope

• Crosshair reticle and centring bracket

• 2-inch eyepiece adaptor

• 1.25-inch adaptor with brass compression ring

• Universal smartphone camera adaptor

• Integrated accessory tray

Technical Specifications

• Optical design: Newtonian reflector

• Primary mirror diameter: 254mm (10 inches)

• Primary mirror shape: Parabolic

• Primary mirror material: Low-expansion borosilicate glass

• Secondary mirror diameter: 58mm minor axis

• Focal length: 1200mm

• Focal ratio: f/5

• Supplied eyepieces: 12.5mm and 20mm, 70° super-wide-angle

• Magnification with 20mm eyepiece: 60x

• Magnification with 12.5mm eyepiece: 96x

• Highest practical magnification: 500x under ideal conditions

• Focuser: 2-inch precision Crayford

• Eyepiece compatibility: 1.25-inch and 2-inch

• Finderscope: 90° angled 9x50 erect-image finderscope

• Mirror coatings: RAQ™ Radiant Aluminium Quartz

• Mirror reflectivity: Up to 94%

• Secondary mirror supports: Four 0.5mm ultra-thin spider vanes

• Tube system: Three-point FlexTube locking system

• Mount type: Manual wooden Dobsonian alt-azimuth mount

• Optical tube material: Rolled steel

• Base diameter: 520mm

• Optical tube weight: 15kg

• Rocker box weight: 12.2kg

• Extended optical tube length: 1120mm

• Retracted optical tube length: 800mm

• Smartphone compatibility: Phones between 54mm and 90mm wide

• Camera connection: Direct SLR camera connection supported

• Light-gathering performance: 56% greater than a 200mm telescope

Who Is the Skyliner 250P FlexTube Best For?

The Sky-Watcher Skyliner 250P FlexTube is particularly well suited to:

• Enthusiastic beginners seeking a powerful first telescope

• Visual observers interested in faint deep-sky objects

• Users wanting greater performance than a standard 6-inch or 8-inch telescope

• Experienced astronomers seeking a capable manual Dobsonian

• Observers who want a large aperture with more practical storage

• Anyone who prefers dependable manual operation without electronics

• Binoviewer users who can benefit from the additional tube-locking position

The Skyliner 250P FlexTube offers an impressive combination of serious light-gathering power, high-quality parabolic optics and practical collapsible construction. For observers wanting memorable views without the complexity of a computerised system, it is a telescope capable of providing years of rewarding exploration.