Used Telescope Buying Guide

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Used Telescope Buying Guide

The gateway to the universe for anyone other than an astronaut is a top-quality telescope. However, systems that are capable of capturing distant stars, planets, and galaxies in fine detail are notoriously expensive. Thankfully, people take such good care of their telescopes that picking up a used model delivers most of the benefits that buying a new telescope does.
Many beginners looking for a used telescope for the first time will often make the mistake of choosing models with the highest magnification capabilities. However, telescopes are not primarily designed to magnify images; they are intended to collect as much light as possible in order to focus it onto a very specific point – in this case, an eyepiece.
The eyepiece, lens and structural identity of a used telescope should all be checked before making a purchase. It is the telescope's lens and aperture that will dictate the quality of images, so it is essential that the lens is in good working order. Magnification – or power – is provided by the telescope's eyepiece, but it is important that the power is not too much for the device's aperture to deal with. Buying a used telescope can be an exciting time for amateur astronomers, but far too many mistake of overpowering their telescope in the assumption that it will deliver better pictures.

The Main Types of Used Telescope

Refractors, Newtonian reflectors, and Catadioptrics telescopes are all currently available in the UK, and all three systems are designed to collect and concentrate light onto a specific point – the eyepiece. However, they all go about in different ways, and that means very different results are possible.

Refractor Telescopes

Refractor telescopes are the most popular type sold in the UK, and they are probably what people picture in their minds when they think of telescopes. They are simple, easy to maintain and relatively easy to use, and that makes them the ideal system for people who are new to star-gazing. They offer a number of advantages over the other types of used telescopes currently available. The sturdy and sealed nature of refractors mean they are often less likely to be damaged when bought in a used condition.

Easy to Use
 

In many cases, a used refractor telescope can be used in minutes by beginners, as they work on a very simple principle. The objective lens remains permanently mounted, so there is usually no need to make technical alterations.

 

Minimal Maintenance
 

The simple premise of refractor telescopes means that there is rarely any need to maintain or calibrate the basic models.

 

A Range of Purposes
 

From plant-watching to deep-space observations, refractors perform well in most situations, and that makes them perfect for beginners.

 

Image Clarity
 

Refractors deliver high-contrast images with the use of only a primary mirror, and they are capable of producing stunning colour depiction at low light levels. The picture clarity is also protected from unwanted air currents, as the tube is completely sealed.

 

Although refractors are the most simply designed used telescopes around, they are often more expensive than the other systems available. Refractors are best left in situ, as they are often too heavy and cumbersome to move around freely. Those wishing to view particularly faint stars in deep space or take photographs will probably be better served with one of the other two types of telescope.

Newtonian Reflector Telescopes

Used Newtonian telescopes use two different mirrors in order to focus light into an eyepiece. A primary, concave mirror is used to bounce light onto a secondary mirror that is angled at 45 degrees. It is easy to identify a Newtonian telescope, as its eyepiece will be located on the side of the device. Newtonian reflectors do need regular maintenance and calibration, but they offer a number of clear advantages over other types of telescope.

Price
 

The cost per square inch of aperture in a Newtonian telescope is lower than the other two varieties. When buying used Newtonian telescopes, buyers will need to check that the device has been maintained and calibrated regularly, however.

 

Mobility
 

Newtonian telescopes are usually the lightest and most compact available, and that makes them ideal for people who intend to move them around the country in order to find the most effective vantage points for star-gazing.

 

Clarity
 

These telescopes are perfect for viewing planets, and they are known to provide exceptionally bright lunar images as well.

 

Newtonian telescopes do sometimes suffer from the image distortion that is created from air currents, as they are not sealed in the way refractors and Catadioptrics are. Although they are lighter and less cumbersome than other types of telescopes, Newtonians are actually more fragile, so buyers should ask plenty of questions of the buyer regarding the condition of used devices. They also require far more maintenance and calibration than the alternatives. The mirrors on a used Newtonian telescope are covered with a very fine film which can also slightly distort the images produced.

Catadioptrics Telescopes

Light flows in three different directions inside used Catadioptrics telescopes, but a larger aperture means more light – and that means pictures of stunning clarity. Light floods through the lens and hits a large, concave mirror. It is then captured by a secondary mirror which, in turn, focuses the light onto the eyepiece. Used Catadioptrics will either be of the Maksutov-Cassegrain or Schmidt-Cassegrain variety, but both work in much the same way.

Dependability
 

This system employs the best aspects of both refractors and Newtonians, as they use lenses and mirrors to focus light. This means they perform well in all situations.

 

Low Maintenance
 

Catadioptrics telescopes are exceptionally easy to use, and that makes them a great used option for beginners. They also require minimal maintenance and no calibration.

 

Picture Clarity
 

These telescopes are perfect for acquiring high-quality pictures of objects in deep space that may look faint when viewed with other models. They are also air-sealed, and that removes interference from air currents completely.

 

Upgradable
 

Modern Catadioptrics telescopes are usually easily upgradable, so adding power where it is needed is rarely a problem.

 

There aren't too many drawbacks to buying used Catadioptrics telescopes that are worth mentioning. They are generally the most expensive type of telescope, but their functionality and high performance in all situations mean that they are often a favourite with experienced star-gazers. The secondary mirror slightly affects light levels, and the rather bulky and stubby appearance of this type of telescope is not what many people expect.

Buying Used Telescopes on eBay

There are thousands of used telescopes available on eBay, and finding many of them is as simple as typing a brief search term into the text-entry box, which can be found near the top of the homepage. However, for more accurate and relevant results, eBay's category-based search facility should be used. Such a search should always begin by clicking the All Categories drop-down menu at the top of the homepage. A menu of broad categories will be presented, and the Cameras and Photography category should be selected. After the Search icon has been clicked, a new page will load with a list of sub-categories on the left. From this list, Telescopes and Binoculars should be selected, and the link for Telescopes should be selected from the subsequent list. From this point, the user can browse the entire list of telescopes on offer; however, these results can be restricted to only used telescopes by clicking the Used check-box on the left of the screen.

Conclusion

The cost-savings that are possible when buying used telescopes are substantial, but care should be taken to ensure that purchases are in full working order; the slightest areas of damage can have a profound effect on the image a telescope can produce. Larger apertures are far more important than magnification, and care should be taken to ensure that the power an eyepiece delivers is not too much for the aperture to cope with. Beginners should choose either a used refractor or Catadioptrics telescope, as they are both far easier to maintain and calibrate. Whatever telescope is chosen, there is no better way to explore that distant worlds that surround us.

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