Pro-Series Tech Info
- "I have used a great number of telescopes; some are good, some mediocre and some bad. To me the Sky-Watcher range of instruments are very good indeed, and suited to amateurs of all kinds – and they are not priced out of the market! Excellent value.
Use them and enjoy them."Sir Patrick Moore CBE FRS (1923 to 2012)
| ||WHAT IS ED? |
Extra-low Dispersion glass allows the optical designer to virtually eliminate chromatic aberration (false color fringing around bright objects), which results in higher resolution and superior contrast in the images.
SKY-WATCHER ED APOCHROMATIC REFRACTORS
Skywatcher Pro-Series ED refractors are built with a two element air spaced objective. The second element is made of ED glass. 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 efforts are 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 a Ronchi* test and a star** test.
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Ronchigrams for lens aberrations
|* 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. |
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