How to Buy a Refracting Telescope?

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How to Buy a Refracting Telescope?

The skies that surround us hold many different surprises and wonders, and the only way to truly explore them is with a telescope. While experienced star-gazers will know exactly what they are looking for, newcomers to the activity may be a little perplexed when they see the choices available.

Before being able to make an informed purchase, it is essential that people understand what telescopes do, and how each design differs. Far too many beginners think power and expense are the most important factors when choosing the best telescope; however, in many cases, too much power can lead to inferior images. Magnification is far less important than the device's aperture; in simple terms, the size of its objective lens.

Telescopes do not operate with the sole purpose of magnifying distant objects; they are intended to collect light. Telescopes that can utilise light in the best way will always deliver the clearest images; magnification just makes the image created larger. Despite the fact that all telescopes work on the principle of collecting light, there are three main types of telescope that use very different methods to do this. These different methods produce slightly different results, and knowing what each variety of telescope is capable of is essential if the correct model for the job is to be chosen.

The most common telescope used in the UK is the refractor. Simple and easy to use; the refractor is what most people imagine when they think of a telescope. However, before making the decision to buy a refracting telescope, it is definitely worth understanding what the other two types of device can offer.

Newtonian Reflectors

A Newtonian reflector telescope is good at providing bright images of deep-sky objects. It uses both an objective lens and two mirrors to bend light towards an eyepiece. This type of telescope is perfect for transporting, as it is lightweight and agile. However, these attributes also make it susceptible to damage during transportation. Newtonian reflectors are generally the cheapest telescopes available, but they are not airtight, and that means air currents can affect the image quality they deliver.

Catadioptrics Telescopes

Catadioptrics telescopes are usually much wider and more cumbersome than refractors, but their larger apertures make them all-round performers. They require little or no maintenance, and they work for both planet-watching and the observation of deep-sky objects. This type of telescope has an air-sealed design, and that means images are not distorted by air currents. Despite the versatile nature of Catadioptrics telescopes, their design is off-putting to some, as the design of a refractor telescope is what most people relate to.

How Refractor Telescopes Work

A refractor uses an objective lens to gather light, and the action of that light bending towards the eyepiece is called refraction. Unlike the other types of telescope, refractors can deliver excellent images at very lower powers. However, the production of large glass lenses is costly, and this makes good-quality refractors relatively expensive. Glass lenses are also known to cause a phenomenon called chromatic aberration which involves objects being surrounded by a halo of colour.
The refractor is the classic telescope design; it is a long tube that can usually be extended in some way. Light enters the glass lens and is gradually refracted until it comes into focus in an eyepiece. This incredibly simple design gives a refractor a number of advantages over the other two types of telescope.

Easy to Use

The simple nature of a refractor means even beginners can start using them within minutes. The objective lens remains fixed in place, and the whole tube is sealed, so manual alterations are never usually required.


Minimum Maintenance

Refractor telescopes are vacuum-sealed, and that protects them from impurities in the air and air currents that could affect the image quality. This means that they very rarely require maintenance any more complicated than a quick wipe of the lens.


Effective When Viewing Terrain

While refractors may not be the best telescopes for viewing distant objects, they are excellent for surveying the surface of the moon and nearby planets.


Image Quality

Refractors are excellent at depicting colour, as telescopes that use mirrors can sometimes produce images with a substantial loss of colour. The fact that the tube is sealed also protects the image from distortion from air currents and impurities.


Refracting telescopes tend to be heavier and more cumbersome than other types, and this can mean transporting them to different vantage points is not always easy. The cost of producing the objective lens means refractors are often relatively expensive, but it is possible to pick up some used refractors from sites like eBay at very reasonable prices. Enthusiasts who wish to view deep-sky objects in detail or indulge in astrophotography may find that a refractor may not be the most effective solution for their needs.

Choosing the Correct Mount for the Job

The modern refracting telescope is far too heavy and cumbersome to be held by hand, and only a good-quality mount will stabilise a refracting telescope sufficiently for detailed images to be at all possible. There are two basic options available, and they deliver different benefits to the user.

Equatorial Mount

An equatorial mount is required for the tracking of diurnal motion. The earth is constantly spinning, and that can mean objects quickly move out of shot. However, an electric drive will keep the refracting telescope pointed directly at the object in order that photographs or detailed examinations can be taken.


Alt Azimuth Mount

This type of mount uses vertical and horizontal controls in order to point the telescope in the required direction. It is generally a more simple solution than the equatorial mount, but it does not deliver the same smooth tracking action.


Eyepieces and Magnification for Refracting Telescopes

Whilst the aperture of a telescope is more important than magnification, there is still a decision to make on the power that is required to magnify the images created by a refractor to the perfect size for viewing. Overpowering these images can actually blur them, so getting this right is absolutely essential. Generally, most refracting telescopes intended for use in the home have a magnification capability of no more than 100x , and no more than 200x. There will be some systems with 400x magnification, but the vast majority of home-based telescopes will struggle to control this power.
It is not unusual for star-gazers to add to their equipment over time, and most refractor telescopes allow for upgrades. This means that people can buy additional eyepieces to deliver extra power when it is required. An eyepiece of between 25mm and 40mm is the norm for viewing deep-sky objects. However, viewing nearby planets and the moon requires an eyepiece of between 4mm and 18mm.

Finding the Telescopes on eBay

Searching for refracting telescopes could not be simpler. The best of way of finding the refracting telescopes that meet the exact requirements of the user is by searching via categories. Such a search should begin with the clicking of the All Categories link near the top of the homepage. A list of categories will then appear in a drop-down menu, and the Cameras and Photography link should be selected, followed by the Search icon. From the list of sub-categories on the left of the page, the Telescopes and Binoculars link should be clicked, followed by the link to Telescopes. The user will then be presented with a comprehensive range of telescopes for sale, but that range can be further reduced by clicking the check-box labelled Refractor.

Conclusion

People who are new to star-gazing often have a romantic notion of what it means to explore the universe, and this draws them to the stereotypical telescope design; that of the refractor. Simply designed and relatively easy to use, a refracting telescope is ideal for beginners or those interested in bright pictures of nearby planets. Consumers should be wary of telescopes with a magnification greater than 200x, as this could actually be detrimental to the picture. Although the very best refracting telescopes can be expensive, they provide a low maintenance option for beginners. The exploration of the universe that surrounds us is now possible from our own homes - but only with the correct equipment.

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