The Sky-Watcher BK 120/1000 OTAW (SW-2005) is an EvoStar optical tube assembly featuring a 120 mm achromatic objective and a 1000 mm focal length. This classic f/8.3 doublet is designed for visual observations of the Moon, planets and deep-sky objects. Anti-reflection coatings on the lenses reduce light loss and help maintain image contrast.
The 120 mm aperture allows observations of lunar craters and mountain ranges, Jupiter's cloud belts and Saturn's rings. Under dark skies, the telescope also enables observations of star clusters, brighter nebulae and galaxies. The visibility of detail depends on atmospheric conditions, light pollution and the magnification used. As with other achromatic refractors, chromatic aberration may appear as coloured fringes around bright objects.
The 2" rack-and-pinion focuser with a 1.25" adapter accepts accessories in both formats. The included Super 25 mm and Super 10 mm eyepieces provide 40× and 100× magnification respectively, while the 90° diagonal makes it easier to observe objects high above the horizon. The 9×50 finder with crosshairs helps aim the telescope at the selected object. The package includes the optical tube and accessories; a mount and tripod must be purchased separately.
• classic 120/1000 mm achromatic doublet with an f/8.3 focal ratio
• anti-reflection coatings on the objective lenses
• suitable for observing the Moon, planets, star clusters and brighter nebulous objects
• rack-and-pinion focuser (2") with a 1.25" adapter
• two included eyepieces: Super 25 mm and Super 10 mm, providing 40× and 100× magnification
• diagonal (2", 90°) with a 1.25" adapter and a 9×50 finder with crosshairs
• mounting bar in the Vixen standard; mount and tripod are not included
• optical tube assembly: Sky-Watcher BK 120/1000 OTAW
• focuser (2") with a 1.25" adapter
• diagonal (2", 90°) with a 1.25" adapter
• eyepiece: Super 25 mm with a 1.25" barrel
• eyepiece: Super 10 mm with a 1.25" barrel
• finder: 9×50 with crosshairs
• mounting bar in the Vixen standard
• manufacturer: Sky-Watcher
• series: EvoStar
• model: BK 120/1000 OTAW
• catalogue number: SW-2005
• product code: TELOTA1201000_SYN
• optical design: achromatic refractor, doublet
• objective diameter: 120 mm
• focal length: 1000 mm
• focal ratio: f/8.3
• optical coatings: anti-reflection
• maximum useful magnification: 240× (catalogue value; the practical range depends on observing conditions)
• magnifications with the included eyepieces: 40× (25 mm) and 100× (10 mm)
• limiting stellar magnitude: 13.0 mag (catalogue value; dependent on observing conditions)
• resolution according to the Rayleigh criterion: 1.19"
• resolution according to the Dawes criterion: 0.97"
• light-gathering power: approximately 294× that of an eye with a 7 mm pupil
• focuser type: rack-and-pinion
• focuser diameter: 2", with a 1.25" adapter
• diagonal: 2", 90°, with a 1.25" adapter
• finder: 9×50 with crosshairs
• mounting bar standard: Vixen
• mount and tripod: not included
• tube length: 1040 mm
• tube diameter: 130 mm
• tube weight: 5.9 kg
• warranty: 60 months
The Sky-Watcher BK 120/1000 OTAW provides a basis for a visual observing setup built around a 120 mm refractor. The included eyepieces offer two magnifications, while the 2"/1.25" focuser format makes it easy to expand the accessory selection later. To begin observing, a suitably stable mount and tripod are required, selected to accommodate the tube's weight and length.
Warning: never observe the Sun through the telescope or finder without a suitable solar filter securely fitted in front of the objective of the instrument concerned. Solar filters are not included.
