Magnificent! This is the largest Skywatcher Newtonian on an equatorial mount. A whopping 254mm /10 inches diameter gives a highest practical magnification of 508x. Appropriately paired with the solid motor driven EQ6 mount. Reflecting telescopes with spherical mirrors often have a defect called spherical aberration. Light rays from the perimeter of the spherical mirror do not focus to the same point as rays from the centre, resulting in images with less sharpness and detail. This problem is not critical for smaller Newtonians, and other reflecting telescopes with focal ratios of f/9 or higher, where the aberration is minimal. However, it becomes more noticeable in larger Newtonians and other reflectors having ratios of f/8 or lower. For larger Newtonians, such as Sky-Watcher the spherical surface of the mirror is altered during polishing to bring the light rays onto a common focal plane. By parabolising the mirror, the images become sharp and detailed, and free of spherical aberration effects. Sky-Watcher parabolic mirror reflectors also feature a four-arm, secondary mirror bracket with fine supports to reduce diffraction spikes. Accurate parabolising, although more difficult and time-consuming, is essential for large Newtonians. If you have opted for a telescope of lower f/ratio or with an aperture of 150mm or more, it is important to look for parabolic mirror or paraboloidal mirror in the specifications. Diameter in mm 254mm Focal Length in mm 1200mm Focal Ratio f 4.7 Optical Design Paraboloidal Newtonian Eyepiece (s) 28mm (50.8mm) Mount Type EQ6 Motorised Equatorial Highest Practical Power 508X Resolving Power (arc sec) 0.45 Motor Drive Both axes built-in Tripod Stainless Steel Accessories Accessory Tray Faintest Stellar Magnitude 14.5 Finder-scope Optical 9x50mm Focuser Diameter 50.8mm & 31.7mm Slow-Motion Control Various speeds by handset Counterweight (s) 2x 5.4