Sky-Watcher 100ED PRO OTA (Optical Tube Assembly) Refractor Product Info

Skywatcher Pro-Series ED refractors are built with a two-element air-spaced objective. The second element is made of the highest grade ED fluorite glass called FPL-53. This premium glass choice is a basic warranty for virtually no false color and for high contrast. The high standard set in material choice is also set in production. No effort is spared to reach optimal optical quality: Our best opticians give each objective a hand pitch polishing finishing touch. This dedication to perfection together with aspheric shaping technology are the best ways to reach a very good wavefront (*) which means virtually no aberrations and textbook star images. The quality of each ED Pro Series objective is monitored by means of Ronchi (*) test and star (**) test.

(*) The essential function of a telescope is gathering starlight without "disturbing" it. This means changing the path of the lightwaves without altering the lightwave itself. Lightwaves all together are referred to as a wavefront. Alterations in this wavefront caused by the optics should be avoided. A wavefront analysis by Ronchi test will show an absence of wavefront alterations if the black and white lines (interference pattern) are perfectly straight and parallel.

(**) The star test proves the ability of the optics to reproduce a pinpoint light source (star) as a pinpoint image. Concentric light circles will surround the pinpoint light dot. These increasingly faint light circles are unavoidable due to diffraction but being well concentric around the central light dot they are a warranty for good optical alignment of the lenses.

Performance of the Sky-Watcher ED Pro-Series refractors surely will both delight and surprise the most critical observer.

Features:

• Diameter: 100mm
• Focal Length: 900mm
• F/ratio: F/9
• Fully Multi-Coated Doublet Objective Lens
• FPL-53 ED Fluorite Glass Objective Element
• Backlash-free 2" Crayford Focuser with Brushed-Aluminium Hubs & rubber grip rings

Specifications:

Package Contents:

• Standard accessories may vary.
• Sky-Watcher 100ED PRO OTA (Optical Tube Assembly) Refractor
• 1.25" LET 20 and 5 Eyepieces