Sky-Watcher Explorer 300PDS

Designed for prime-focus astrophotography while providing excellent visual performance, the Sky-Watcher Explorer 300PDS uses a 305 mm parabolic Newtonian optical system with a 1500 mm focal length and f/4.9 focal ratio.

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

305 mm Parabolic Primary Mirror

The primary mirror has a diameter of 305 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.

Large Aperture for Deep-Sky Observation

With its 305 mm aperture, the Explorer 300PDS provides substantial light-gathering capability.

Sky-Watcher states that it gathers 44% more light than a 250 mm Newtonian.

This aperture is particularly useful for observing and imaging galaxies, nebulae and star clusters.

Low-Expansion Borosilicate Mirrors

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

This material promotes faster thermal equilibrium and helps the mirrors retain their correct shape during cooling.

1500 mm Focal Length and f/4.9 Focal Ratio

With a 1500 mm focal length and 305 mm aperture, the Explorer 300PDS operates at f/4.9.

This configuration is well suited to deep-sky astrophotography while retaining substantial focal length for detailed visual observation.

2-Inch Dual-Speed Crayford Focuser

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

The 10:1 reduction allows rapid coarse adjustment followed by much more precise fine focusing, particularly useful for critical astrophotography focus.

The focuser also incorporates an M54 internal thread.

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 astronomical eyepieces and accessories.

Radiant Aluminum Quartz RAQ Coating

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

The coating 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.

70 mm Secondary Mirror

The secondary mirror has a 70 mm minor axis.

It is supported by four 0.5 mm thin spider vanes designed to minimise obstruction of the optical path and reduce diffraction spikes.

Fully Collimatable Optics

Both primary and secondary mirrors are fully collimatable.

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

Rigid Internally Darkened Tube

The optical tube is manufactured from rolled steel and features an internally darkened finish.

This construction helps reduce unwanted internal reflections while providing the mechanical rigidity required for an optical tube of this size.

Optional Coma Corrector

Sky-Watcher offers an M48 coma corrector matched to the PDS range to improve star correction towards the edge of the imaging field.

The coma corrector is available separately.

28 mm LET Eyepiece

A 28 mm 2-inch LET eyepiece is supplied with the optical tube.

It provides approximately 53× magnification with the Explorer 300PDS's 1500 mm focal length.

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.

75 mm Losmandy-Style Dovetail

Due to its size and weight, the Explorer 300PDS uses a 75 mm Losmandy-style dovetail bar.

Tube rings are supplied with the optical tube.

Camera Adapter

A piggyback DSLR camera mounting adapter is supplied.

It complements the imaging capabilities of the PDS optical tube.

Mounting a 23 kg Optical Tube

The stated optical tube weight is 23 kg.

Sky-Watcher specifically recommends the CQ350i Pro and EQ8-R Pro mounts for this instrument.

Technical Specifications

• Manufacturer : Sky-Watcher
• Model : Explorer 300PDS
• Product code : 10222
• Type : Newtonian telescope optimised for imaging
• Primary mirror diameter : 305 mm
• Primary mirror : Parabolic
• Focal length : 1500 mm
• Focal ratio : f/4.9
• Mirror material : Low-expansion borosilicate glass
• Secondary mirror diameter : 70 mm
• Mirror coating : Radiant Aluminum Quartz RAQ
• Stated reflectivity : 94%
• Secondary mirror supports : Four 0.5 mm vanes
• Focuser : Crayford
• Focuser size : 2 inch
• Reduction ratio : 10:1
• Focuser internal thread : M54
• Eyepiece compatibility : 1.25 inch and 2 inch
• Supplied eyepiece : 28 mm 2-inch LET
• Magnification with supplied eyepiece : 53×
• Highest practical power stated : 610×
• Finder : 9 × 50 with crosshair reticle
• Collimation : Adjustable primary and secondary mirrors
• Optical tube : Internally darkened rolled steel
• Dovetail : 75 mm Losmandy style
• Camera adapter : Included
• Optical tube weight : 23 kg
• Stated light gathering compared with 250 mm : +44%

Package Contents

• Sky-Watcher Explorer 300PDS optical tube
• Tube rings
• 75 mm Losmandy-style dovetail bar
• 28 mm 2-inch LET eyepiece
• 9 × 50 finderscope with crosshair reticle
• 1.25-inch eyepiece adapter
• 2-inch eyepiece adapter
• Camera adapter