Sky-Watcher Quattro 250P

Designed primarily for astrophotography, the Sky-Watcher Quattro 250P uses a 254 mm parabolic Newtonian optical system with a 1000 mm focal length and fast f/4 focal ratio.

Its large aperture, low-expansion borosilicate mirrors, dual-speed 2-inch Linear Power focuser and rigid internally darkened tube make it particularly suitable for deep-sky imaging.

The Quattro 250P can also be used for visual observation through its compatibility with standard 1.25-inch and 2-inch eyepieces.

254 mm Parabolic Primary Mirror

The primary mirror has a diameter of 254 mm and a parabolic surface.

This geometry brings incoming light rays to the same focal point and eliminates the spherical aberration associated with spherical mirrors used at fast focal ratios.

Sky-Watcher specifies diffraction-limited optics designed to produce sharp, high-contrast and detailed images.

Fast f/4 Focal Ratio

With a 1000 mm focal length and 254 mm aperture, the Quattro 250P operates at f/4.

This fast focal ratio is one of the defining characteristics of the Quattro range and allows imaging data to be collected efficiently.

The configuration is particularly suitable for imaging galaxies, nebulae and star clusters.

Large Aperture for Deep-Sky Imaging

With its 254 mm aperture, the Quattro 250P provides substantial light-gathering capability.

Sky-Watcher states that it gathers 56% more light than a 200 mm instrument.

This aperture provides a significant advantage when observing and imaging faint deep-sky objects.

Low-Expansion Borosilicate Mirrors

Both primary and secondary mirrors are manufactured from low-expansion borosilicate glass.

This material allows the mirrors to reach thermal equilibrium more quickly and helps them maintain a more stable shape during cooling.

This thermal stability is particularly valuable during long imaging sessions.

Radiant Aluminum Quartz RAQ Coating

The primary and secondary mirrors feature Sky-Watcher Radiant Aluminum Quartz RAQ coatings.

The coating system combines reflective aluminium, a dielectric tantalum pentoxide layer designed to improve reflectivity and durability, and a protective silicon dioxide layer.

Sky-Watcher specifies 94% reflectivity.

82 mm Secondary Mirror

The secondary mirror has an 82 mm minor axis.

It is supported by four 0.5 mm thin spider vanes designed to minimise obstruction of the optical path while maintaining good mechanical rigidity.

2-Inch Dual-Speed Linear Power Focuser

Focusing is provided by a 2-inch dual-speed Linear Power focuser.

The drawtube is supported by four precision ball bearings to provide excellent mechanical stability and minimise image shift when supporting a camera or heavy accessory.

The 10:1 reduction system allows highly precise fine focusing, particularly important for astrophotography.

1.25-Inch and 2-Inch Compatibility

Adapters for both 1.25-inch and 2-inch eyepieces are supplied.

This provides compatibility with a wide range of imaging accessories and astronomical eyepieces.

No eyepiece is supplied with the optical tube.

Rigid Internally Darkened Tube

The optical tube is manufactured from rolled steel for good mechanical rigidity.

Its interior is darkened and incorporates internal knife-edge baffles designed to reduce stray light and improve contrast.

Fully Collimatable Optics

Both primary and secondary mirrors are fully collimatable.

The primary mirror cell incorporates large knurled adjustment knobs for convenient collimation.

9 × 50 Finderscope

A fully multi-coated 9 × 50 optical finderscope is supplied.

It incorporates a crosshair reticle and centring bracket for alignment with the main optical tube.

Mounting

The optical tube is supplied with tube rings and a 45 mm dovetail bar.

A piggyback DSLR camera mounting adapter is also included.

With a stated optical tube weight of 15 kg, the Quattro 250P requires a mount with suitable payload capacity.

Technical Specifications

• Manufacturer : Sky-Watcher
• Model : Quattro 250P
• Product code : 10239
• Type : Newtonian astrograph
• Primary mirror diameter : 254 mm
• Primary mirror : Parabolic
• Focal length : 1000 mm
• Focal ratio : f/4
• Mirror material : Low-expansion borosilicate glass
• Secondary mirror diameter : 82 mm
• Mirror coating : Radiant Aluminum Quartz RAQ
• Stated reflectivity : 94%
• Secondary mirror supports : Four 0.5 mm vanes
• Focuser : Linear Power
• Focuser size : 2 inch
• Reduction ratio : 10:1
• Drawtube support : Four precision ball bearings
• Eyepiece compatibility : 1.25 inch and 2 inch
• Supplied eyepieces : None
• Highest practical power stated : 508×
• Finder : 9 × 50 with crosshair reticle
• Collimation : Adjustable primary and secondary mirrors
• Optical tube : Internally darkened rolled steel
• Internal baffles : Yes
• Tube rings : Included
• Dovetail : 45 mm
• Camera adapter : Included
• Optical tube weight : 15 kg
• Stated light gathering compared with 200 mm : +56%

Package Contents

• Sky-Watcher Quattro 250P optical tube
• Tube rings
• 45 mm dovetail bar
• 9 × 50 finderscope with crosshair reticle
• 1.25-inch eyepiece adapter
• 2-inch eyepiece adapter
• Camera adapter