There are many types of telescopes, the more popular ones being x-ray telescope, ultraviolet telescope, infrared telescope and optical telescope. X-ray telescope uses the range of wavelength of light shorter than ultraviolet. Ultraviolet telescope uses the range of wavelength shorter than the visible light. Infrared telescope uses the range of wavelength longer than the visible light. Optical telescopes use the visible light spectrum. Other types include the sub-millimeter telescope that uses wavelengths longer than infrared light, Fresnel Imager which is a specific technology for optical lens, X-ray optics which uses some wavelengths shorter than ultraviolet light. There are gravitational wave telescope and neutrino telescope as well.
While a telescope in general is in fact an optical device or instrument which helps in observing or seeing remote objects using electromagnetic radiation, an optical telescope uses the visible spectrum of light as seen or observed by the naked human eye. Optical telescopes gather and focus on visible light to form a magnified image of an object and allow a direct view. This visual can be in the form of a photo or moving images. Electronic image sensors can also be used to collect and analyze the data. Optical telescope has three variants. One type uses lenses and hence classified as refractors. One uses mirrors and hence classified as reflectors. The third type combines mirrors and lenses. These are called catadioptric telescopes.
List of Pros of Optical Telescopes
1. Affordable and Available.
Optical telescopes use mirrors or lenses or both. They work with visible light which is the easiest to observe. The materials and the mechanisms are among the simplest. Optical telescopes are cheaper to make and hence more affordable for buyers. The cost and also the nature of its use ensure it is a commonly used device. In other words, they are widely available. You would not have to ransack niche stores or look out for that one company in the world making the instrument.
2. Easy to Use.
Optical telescopes are very convenient to use. They used to be very large before but today you can get small portable ones. It is true that the smaller ones aren’t amazing because they capture very little light so the viewing pleasure is adversely affected. However, you can carry one around, use it anywhere or anytime. There is no restriction to carrying or using optical telescopes. You would need licenses for some types of telescopes.
3. Visual Treat.
Optical telescopes are a visual treat. You would get to see amazing live pictures or images of space, you can focus on a few stars or a cluster, you can look for specific planets or other celestial objects. You can use optical telescopes to capture images and you can then frame these photos for your family and friends to see. Other technologies used in telescopes offer images that may not mean much to most people.
List of Cons of Optical Telescopes
1. Challenge of Weather and Atmospheric Turbulence.
Optical telescopes use visible light which is almost always subject to the influence of local conditions, most notably weather. There are manmade or artificial influences that will impair how visible light is observed and understood but weather remains a larger threat. If direct line of sight is impaired, if the visible light is minimal or weather affects the quantum of light reaching the device then optical telescopes will not function even remotely as they do on a clear night sky. Also, the weather is not confined to the troposphere or stratosphere but spans ionosphere and exosphere before space events play spoilsport. Any kind of turbulence in the higher levels of the atmosphere can affect the light reaching the telescope.
2. Unusable during the Day.
Since visible light is the key component for optical telescopes to work, one has to depend on darkness. Daytime viewing is difficult as the mighty sun and its glorious light makes distant stars almost impossible to observe. Nighttime viewing is amazing but not everyone can stay up late at night for a celestial adventure.
3. Great Optical Telescopes are Big and Heavy.
The best optical telescopes are quite big in size. They are not easy to carry around. In fact, you can forgo portability. You will need to dismantle the whole piece, carry it in your car or van and then set it up at the site where you wish to be. This is both time consuming and laborious. The smallest ones have very little light reaching the lens, mirror or both so they don’t offer vast panoramas or vistas. The big ones or the more advanced ones are also heavy. Many are almost impossible for a single person to carry. Of course there are lighter variants but the big ones are usually installed at one place, not meant to be moved unless it is being shifted onetime to another observatory.