HantsAstro Classes

HantsAstro

Sky-Watcher Explorer 130/900 f7


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Sky-Watcher Explorer 130/900 Reflector


Magnifications (with optics supplied): x36, x72, x90, x180
Highest Practical Power (Potential): x260
Diameter of Primary Mirror: 130mm
Telescope Focal Lengh: 900mm (f/6.92)
Eyepieces Supplied (1.25"): 10mm & 25mm
x2 Barlow Lens
Red Dot Finder
EQ2 Equatorial Mount + Clock Drive
Aluminium Tripod with Accessory Tray
30% more Light Gathering than 114mm



The Explorer 130/900 Newtonian reflector is one of the UK is best-selling entry-level telescopes.
This version has a focal length of 900 mm, which makes it F7, which is an ideal speed of a general observing. There is also a short tube version with a parabolic primary mirror, which has also proved popular. They are usually sold with an EQ1 mount and a clock drive for basic tracking. The 900 mm version is available for £119 and 650 mm version with the motor drive for about £155. There are many pros and cons between the different types of mirrors, but the main advantage with a 900 mm version is that it is not so sensitive to collimation and for our purposes is much easier to maintain

Newtonians (also known as catoptrics) usually use a concave parabolic primary mirror to collect and focus incoming light onto a flat secondary (diagonal) mirror that in turn reflects the image out of an opening at the side of the main tube and into the eyepiece. The basic design has been around for hundreds of years and invented by, you guessed it Sir Isaac Newton in 1689.

A bit like the picture above his one was a 150mm diameter and used his discovery of Newton's Rings to grind and check that the mirrors flat.

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