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I AM NOT A DEALER! I’m just a regular member of the public who bought the wrong model for a friend’s birthday, and now I have one too many telescopes. I was overwhelmed by the number of different descriptions on eBay for the same telescope. What do the numbers mean? Is parabolic better? What’s the f-stop? What does the motor do? If you’re as confused as I was, maybe this will help:
SKYWATCHER: this is the manufacturer. Based in China, they’re one of the largest manufacturers of telescopes in the world. I’ve heard that they also supply most of the parts for the Celestron telescopes, their main rival in consumer telescopes (although I haven’t been able to verify this).
NEWTONIAN / REFLECTOR: Newtonians and their variant, the Dobsonian, are types of reflecting telescopes. Using a simple concave primary mirror design with a flat secondary, Newtonian designs have the advantage of being inexpensive to produce, but they also provide a crisp view. These simple designs are highly popular among amateur astronomers worldwide. REFRACTOR telescopes are of a different (and older) design, and are usually more expensive.
EXPLORER: this is the name of a range of telescopes from SKYWATCHER, for the European market. In the USA, the same model does away with the EXPLORER name, and is called the BK1309.
130: This is the diameter of the aperture in millimetres. This is where the light enters the telescope, and bigger is usually better.
130M: For SKYWATCHER telescopes, there are various configuration options. The ‘M’ stands for ‘Motorised’, which means that a small single-axis motor (the ‘RA Motor Drive’) is included, along with a hand-held controller. This is designed to help you track objects over time. The motor unit is worth about 60. Not to be confused with the EZ or GOTO motors, which are (usually) optional extras and linked into computerised star-charts to allow you to GOTO a point in the sky immediately. The item I have for sale is NOT motorised.
130P; The ‘P’ stands for ‘Parabolic’ which is the shape of the primary mirror. A parabolic mirror Without the ‘P’, the mirror will be of the usual spherical type. Parabolic primary mirrors, normally found in larger more expensive telescopes, help to eliminate spherical aberrations, producing even sharper, higher-contrast images which are full of detail. A parabolic or more accurately a “paraboloidal” mirror, is ground to a shape which brings all incoming light rays to a perfect focus, on axis. The item I have for sale is NOT parabolic,.
900 is the focal length, given in millimeters. Sometimes, the inch equivalent is used which in this case is 5.1 inches. Confusingly, some people just use the f-stop number in place of this measurement.. For my particular model, the f-stop is f/6.92. This ‘larger than usual’ figure makes up for not having a parabolic mirror. The focal length of the 130P model is 650mm, not 900.
EQ2: This is the type of mount (the assembly at the top of the tripod). There are two main types of mount, the ‘ALT-AZ’ (short for ‘Altitude-Azimuth’) and the’EQ’ (short for ‘Equatorial’). The ALT-AZ is a simple up/down (Altitude) and left/right (Azimuth) mount, just like a camera tripod. However, simple left/right doesn’t correspond with the position of celestial bodies, and results in ‘field rotation’ The EQ mount has one axis parallel to the earth’s polar axis, which eliminates this effect. The item I have for sale uses the EQ2 mount, which is the standard Skywatcher equatorial mount at this price point.
FINDER: You need one of these to point the way. Most consumer telescopes come with a finder pre-fitted, usually a red-dot or laser type. Optical finders are available as separate items and can replace the pre-fitted one. My item has a RED-DOT finder.
IMPORTANT! Please check CAREFULLY the exact spec of any telescopes you purchase online. Some dealers don’t know their products too well and I’ve seen configurations such as 130MP/900mm which simply do not exist.
Category: Cameras and Photography:Telescopes and Binoculars:Telescopes
Location: Clacton-on-Sea
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