PARABOLIC PRIMARY MIRRORS

 

Features High-Quality Parabolic Primary Mirrors to eliminate spherical aberrations inherent in 'fast' focal length reflectors with spherical primary mirrors. The mirrors are parabolized to bring all the light rays to the same focal point to give sharp, contrasty images, which are full of detail.

 

SKY-WATCHER DELUXE MIRROR COATINGS

 

Most reflectors today usually have a coat of aluminum as the mirror surface and then an overcoat of silicon monoxide or silicon dioxide to protect it. Silicon dioxide produces a much more durable coat than silicon monoxide but requires specialized equipment to apply it and is, therefore, more expensive. Protection is needed, because, in most reflectors, the mirror is open to the elements and deterioration of the reflective layer reduces the resolution of the telescope. ALL Sky-Watcher reflectors are Multi-Coated with Silicon Dioxide as a standard for Optimum Durability and Long Term Performance.

 

• Newtonian Reflector

• Aperture: 458 mm (18'')

• Focal Length: 1900 mm (74.8 in)

• Focal Ratio: f4

• Central Obstruction: 120 mm, 26% 

• Light Gathering Power: 4266x

• High quality/precision parabolic mirror

• Low-expansion borosilicate glass for both primary mirror & secondary mirror

• For visual observing up to 914x practical magnification (Lowest Useful magnification 65x)

• 0.25-arc second resolving power (Dawes) and 0.28 arc seconds resolving power  (Rayleigh) & 16 stellar magnitude

• Portable, quick-assemble truss structure

• Fully Illuminated Field: 44 mm (1.7 in)

• Optical Tube Length: 1940 mm (76.4 in)