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Telescopes Buying Guide

Did you know that you can see the Milky Way with the naked eye in certain “dark sites” in the UK? What if you want to see it up close, or look even deeper into space? For that, you’ll need a telescope.

 

Buying your first telescope isn’t as difficult as it sounds. Let our simple guide help you to start exploring the night sky. A Dark Site is an area with particularly low levels of light pollution, leaving clear, dark skies. These offer the best views for astronomers, and are usually in more rural areas. Dark Sky Discovery is a UK based site with a map of ideal stargazing locations.

When you buy your first telescope, we also recommend getting a planisphere and a simple star map or guide. These will help you to navigate the night sky and make sense of what it is that you are looking at.

Telescopes work by gathering light. A telescopes power isn’t measured by its magnification, but by the aperture, aka the diameter of the main lens or mirror. Like in photography a larger aperture, means more light. But in astronomy aperture is referred to as a measurement in millimetres or inches. Telescopes are often named in the same way. For example the Celestron Astromaster 76 EQ has a 76mm aperture.

Magnification

Magnification changes depending on which eye piece you are using with which telescope. To work out the magnification or power of an eyepiece when used with your telescope, you simply divid the focal length of the telescope by the focal length of the eyepiece. These measurements can be found in the specifications for each item.

Example: Celestron AstroMaster 76EQ comes with two eyepieces. The focal length of the telescope is 700mm. The first eyepiece focal length is 20mm. This would therefore give a magnification of 35x.The second eyepiece has a focal length of 10mm, giving a magnification of 70x.

You can buy additional eyepieces to change the magnification.

There are two main types of telescope – refractors and reflectors.

Refractor telescopes

refractor-telescope

Refractors use a lens to produce the image you see with your eye. You look through an eye piece at the end of the tube, at the focussing point of the refracted image. It’s similar to how a pair of glasses work, but on a much larger scale. They look like a stereotypical telescope, long and thin. They produce a high contrast image, but the image is dimmer than a reflector.

They require the least maintenance, and smaller models are light enough to mount on a camera tripod, making them great “grab and go” telescopes. Because of this, their ease of use and their simple, robust design, they are ideal telescopes for beginners. In dark locations a Bushnell Voyager 70x800mm Telescope will show the moon’s craters, Saturn’s rings and even some distant galaxies and even features “SkyTour” a built in voice tour of the night sky – great for beginners.

Reflector Telescopes:

reflector-scope

Reflectors use a system of mirrors to produce an image. This type of telescope tends to be shorter, but have a larger diameter. They’re therefore much more compact if space is an issue. But, they are much more delicate and if transporting from site to site, they will need “collimating” (essentially, calibrating the mirrors) before each use. Their larger aperture makes these telescopes brighter, and therefore better for viewing very distant or dimmer celestial objects.

The Bushnell NorthStar 114 x 900mm Motorised Go To Telescope is a reflector telescope with a motor drive. This allows easy tracking of stars as they move across the sky and even comes with a simple to use module which automatically locks on to one of over 20,000 celestial bodies with just the press of a button. The 114mm aperture means it offers a bright image.

Mounts

You might have noticed that all 3 Celestron models mentioned above were followed by the letters “EQ”. The letter following the model name and aperture size refers to the type of mount that comes with the telescope. To a photographer, a mount is a type of tripod. But, there are different types available:

Alt-azimuth (AZ)
A very simple mount which moves up and down and left to right. The name is a combination of “altitude” (up and down) and azimuth (left and right).

Equatorial (EQ)
An equatorial mount takes into account the movement of the earth. One of the mount’s axes is aligned parallel to the Earth’s axis and using either a small motor or a weight-driven system, the mount follows the stars as they move through the stars.

Go-to-mounts: (SLT)
A go-to-mount has a motor attached to both the altitude and azimuth (up and down, left and right) axes. The two motors are connected to an on-board computer. These can locate objects and track them using large star databases. An example of this is the Celestron NexStar 130SLT.

Astrophotography

astro-imaging

Did you know that you can easily connect your DSLR or CSC to most telescopes?

All you need is a T mount adapter or camera adpater and a T2 adapter. The T mount adapter attaches to your telescope, where the eye piece goes. The T2 adapter goes onto your camera lens mount and allows you to connect your camera to your telescope.

Instead of using your camera’s lens, you use the telescope as a lens – allowing you to take pictures the stars. Of course, you could also use it to take pictures of the land, but remember than many telescopes have an inverted image – so the building you are looking at may appear upside down!

Getting started:

The Philip’s Practical Astronomy Kit contains a 3-in-1 beginners guide to astronomy. It includes a planisphere and makes an ideal gift to go alongside a telescope but can also be used to identify stars with the naked eye all year round.

first-view2

An ideal gift for children is the Celestron FirstScope. The simple table top design is small and very easy to use.

All our Celestron and Bushnell telescopes feature a quick and easy setup.

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