Telescopes are instruments used primarily to study the stars and other heavenly bodies, but they also have other diverse applications such as rifle scopes. There are numerous telescope accessories in the market with some being essential to the mechanism of the telescope, and others being luxury additions. Mounts and tripods are some of the most essential telescope accessories. Interestingly though, there are telescopes that do not come with the tripod and mount. Below is a list of telescope accessories that any stargazing enthusiast should have in their possession.
Image orientation doesn’t really matter in astronomy. Telescopes usually present upside-down or inverted images. This has been a challenge right from the days of Galileo who invented the first telescope. Advances in technology have resulted in prism diagonals that are used to right the image. When cassegrain and refractor telescopes are paired up with the standard 90° star diagonal the resulting image is usually mirror reversed and right-side-up. This presents problems pertaining to the use of star charts. This problem is also corrected using the erecting prisms. Erecting prisms however do not work with refractor telescopes.
Prisms are therefore an essential telescope accessory since a telescope user will run into mirror images at some point. However, mirror images become a problem only when you intend to use printed materials as navigation aids. There are computerized telescopes that are able to flip the mirror images and are therefore easier to use especially when tracking planets and constellations.
Astronomy telescopes have objective lenses which help in the gathering of light and the creation of a well focused and sharp image. The telescope’s eyepiece magnifies the object to be viewed and is composed of several lenses. Older telescopes used to have a relay system which was used in correcting mirrored images. As a result, these telescopes used to be quite long. Currently, erecting prisms have replaced the relay system resulting in shorter and more powerful telescopes.
Barrow lenses are vital telescope accessories since they increase the focal length of the primary mirror or objective lens. They also double or triple the magnification power of the eyepiece. Achromatic lenses are double layered glass used as objective lenses in most telescopes. They eliminated rainbow images as well as the distorted ones. The distortion is usually associated with non achromatic lenses.
According to the American Astronomical Society (AAS), superior telescopes are not necessarily designated by the power of the objective lens. Astronomers pay little attention to a telescope’s magnification power. Apart from being able to identify achromatic lenses, it is also vital that your telescope be equipped with an optical coating. This allows for maximum light intake which directly impacts the clarity of the image to be viewed.
The eyepiece in a telescope has to gather as much light as possible if you are to view clear images. This telescope accessory is governed by the telescope’s f-ratio. Telescopes bearing an f-ratio of f/10 are able to produce a clear image without the use of a specific eyepiece. However, telescopes that bear a rating of f/4 will need a special kind of eyepiece. The eye relief is an important aspect when shopping for a telescope eyepiece. It is the distance that separates the eyepiece lens and your eye. By and large, the eye relief determines whether or not you are able to have a good field of view. If you wear eyeglasses, the recommended eye relief is 15mm. The field of view of the eyepiece is calculated from the eyepiece’s apparent view divided by the magnification of the eyepiece. Magnification of the eyepiece may not be all that important when buying an eyepiece for your telescope; however, it has to be considered nonetheless.
Once you have a good idea of the magnification level that you desire, then figuring out the focal length of the eyepiece becomes rather easy. The eyepiece is indeed one of the most important telescope accessories as it houses the aperture which lets in light for a clear image. The exit pupil and power/inch are two important factors that determine the size of the aperture. The amount of light rays leaving the eyepiece is what forms the exit pupil.
These telescope accessories are purchased along with the eyepieces. Telescope filters are not vital to the functioning of the telescope. They are screwed onto the eyepiece barrel and greatly enhance the stargazing experience. There are three main types of telescope filters; light-pollution filter, colored filter and moon filter. Colored filters are responsible for enhancing planetary and lunar details. They have varying colors which greatly reduce wavelength distortion that usually results in blurred images. Light pollution filters blocks out sodium and mercury vapour and allows in oxygen III and hydrogen beta which are wavelengths from deep space. The moon filter accentuates lunar details by limiting lunar light.
Solar filters enable the risk free observation of the sun by filtering out approximately 99.9 percent of solar light. You get to view the blazing sun without risking serious damage to the eyes or even blindness. Variable-polarizing filters function just like a dimmer switch. They lessen the amount of light coming in from overly bright cosmological bodies by as much as 40 percent. They are equipped with a rotating filter. Generally, filters are best suited for people who are interested in studying the sun or anyone who wishes to observe the stars more closely.
Amateur telescopes are usually mounted with equatorial and altazimuth mounts. As mentioned previously, mounts are vital telescope accessories. Observing the different constellations and other cosmological bodies would be virtually impossible without the support of the mounts. The Dobsonian mount is categorized under altazimuth mounts. It is wooden and quite sturdy. Altazimuth mounts are synonymous with amateur astronomers. They have horizontal and vertical motion axes also known as azimuth and altitude respectively. Its build is similar to a typical camera tripod. They are cheap and easy to use.
Equatorial mounts on the other hand are used extensively by professionals and hobbyists. They can be motorized for automated sky tracking. Some telescope accessories are a must have while others are just fun to have. The non vital telescope accessories can be acquired in any order, and it would depend on your passion and level of knowledge in astronomy.
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