How To Buy A Telescope – All Major Factors To Consider

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For any young and budding astronomer, the telescope is a weapon with which they can inspect the mysteries of the universe. The excitement of getting your first telescope is unparalleled. However, sometimes it is in this excitement that people end up buying the wrong type of telescope. 

Manufacturers sometimes make tall claims, but the telescope is unable to provide the experience you expect. You must assess all parameters of a telescope, as per your requirements. In this article, we will share some tips that can help you understand how to buy a telescope. 

High Power Is Not Always Good

Many people think that it is always good to buy a high-power telescope. However, power is not the only parameter that makes a telescope suitable. Many advanced telescopes that provide up to 500 times magnification are only good for enlarging the celestial bodies. The light reflected from the objects enters the telescope and gets dispersed in a wider field. Therefore, the image gets magnified but not illuminated. So, you see a faint picture in the eyepiece. 

Moreover, when you buy a high-power telescope, you need to search a lot for the perfect eyepiece as well. The common belief that buying a high-power telescope is always the best option is false. Sometimes, even low-power telescopes with the right eyepiece can help you get the perfect view. 

Selecting The Eyepiece

With every new telescope, you should get at least one eyepiece. Some telescope manufacturers provide two or three eyepieces of different ranges as well. For proper magnification, a decent eyepiece is essential. The eyepiece is rated in terms of millimeters. An eyepiece of a higher millimeter rating provides lesser magnification. Generally, a 25-millimeter eyepiece is suitable for beginners. 

Just like power, a higher eyepiece rating does not guarantee a better image. Moreover, when you choose an eyepiece with a higher rating, it ultimately reduces the field of vision. Thus, when you look at a nebula, for instance, you will only see a focussed image of a small cluster. To ensure that an object remains in view when you use a higher rated eyepiece, you will need a motorized mount. 

By using an eyepiece of a lower rating, you will get a wider field, requiring less light to view the image. Thus, you can even see dim objects. 

In astronomy, you need both kinds of eyepieces. No particular type of eyepiece is the most suitable one. It entirely depends on how you want to see the objects. 

Selecting The Aperture

In a refractor telescope, the diameter of the objective lens is called the aperture. Similarly, the diameter of the objective mirror in a reflector telescope is called its aperture. 

Aperture is the most critical parameter that decides the power of the telescope. Wider the aperture of the telescope, more the light that enters into the eyepiece. Therefore, the right aperture width is essential to get a clear image.

However, it does not mean that you should buy the telescope with the largest aperture. Telescopes with larger lens or mirror diameters are too big and become inconvenient to use. Therefore, you should select a telescope whose aperture is wide, but at the same time, its size should be suitable for your needs. 

Selecting The Focal Ratio

The focal ratio is also an important parameter that governs the amount of magnification. It is the ratio between the focal length and the aperture width. The focal length is generally written on the telescope lens or mirror. The higher the focal ratio, more the magnification produced in the image. 

Choosing A Mount

The telescope mount is the part that holds the telescope steady while scoping. Buying a low-quality telescope mount just because it is an add-on accessory is not good for the viewing experience. A substandard one cannot hold the telescope steady, and thus, the field will keep getting disturbed. 

Telescope mounts are of two types. The first is the equatorial telescope mount that continuously moves the telescope with the movement of the object in focus. The high-end equatorial telescope mounts have a motor that helps in facilitating this movement. Modern equatorial mounts come with a small computer that helps in projecting the image on a screen.

The second type of telescope mount is the altazimuth mount. These are more common and keep the telescope steady, allowing only limited movement. These mounts act as a tripod stand, letting the telescope move upwards, downwards, backward, and forwards only. 

Price Of The Telescope

Your objectives for using a telescope should be clear before you go out to buy one. While the most expensive telescopes have remarkably better features, they might not be suitable for your needs. Many stores offer cheap telescopes that usually do not serve their purpose either. Do not waste your money buying such items. 

In the case of telescopes, you usually get what you pay. So, decide why you want to buy a telescope, then choose one as per your requirement. 

Which Type Of Telescope Should You Buy

There are two primary types of telescopes available for amateurs. The first is the refractor telescope that has two lenses to focus the image. The first lens is the objective one, while the second is called the eyepiece.

The second type of telescope is the reflector telescope. It uses a concave mirror to focus the light at the bottom of the optical tube. Both telescopes have notable benefits. Refractor telescopes are better for viewing the moon and the planets. The best refractor telescopes also provide a contrast planetary view. Reflector telescopes do not suffer from chromatic aberration, a common problem with refractor telescopes. 


So, in this article, we gave you some tips on how to buy a telescope. Manufacturers and salespersons often make misleading remarks about their products. You should search for a store that has a wide variety of telescopes, and a knowledgeable salesperson who can guide you through the purchase. 

It is important to understand your objectives behind buying a telescope. Different sets of eyepieces, mounts, etc. fulfill different types of goals. You should take a feel of the telescope before buying it. Sometimes, even with all the correct parameters, the scope doesn’t feel suitable for use. If you purchase an excellent telescope once, it will serve you for years altogether. 

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