Refractor Telescopes and Their Benefits
Ever since Galileo first invented the refractor telescope in the early 1600's, human beings have had a thirst to see the stars and planets close up. The first refractor, consisting of a convex objective lens at the base of a tube and a convex eyepiece at the top was actually first introduced in 1608 but perfected by Galileo in 1611. When we look into the night sky with our naked eye, it is hard to believe that just a couple of lenses could allow us to see the features of Jupiter, or the rings of Saturn or the billowing clouds of distant nebula, but it's true. If you love gazing up at the stars then getting a telescope is an investment you can't do without. But which kind of telescope should you buy?
There are basically 2 kinds of telescopes - reflector telescopes and refractor telescopes. As their names suggest, the reflector uses mirrors to reflect incoming light back to the eyepiece, while refractor uses lenses to refract or bend the light towards the eyepiece. In the movies, when you see Captain Ahab of the Moby Dick whip out a tube to look into, this is what a refractor telescope looks like.
This kind of telescope is the most common type of telescope for the amateur astronomer, and they are very good telescopes, but like anything else you might consider buying, there are always pros and cons.
Advantages of Refractors
One of the best features of these telescopes is that there is virtually no maintenance involved because there are no mirrors to clean or keep aligned. Also, it is a closed system so no moisture or dirt can get into the tube. It is one of the most rugged telescope designs and is easily transported. Also this type of telescope is good for daytime viewing such as looking at scenery or for bird watching. These telescopes are also generally lighter and easier to handle per inch of aperture and therefore easier for children to use.
Disadvantages of Refractors
However, these telescopes are by far the most expensive telescopes per inch of aperture. Also, lenses inherently disperse light into colors which will distort the incoming image. This is called chromatic aberration. There are apochromatic lenses that can correct this problem, and with this correction, these telescopes will give a fantastic image, but the price goes up dramatically when these lenses are employed. After about 3 inches of aperture, the price goes up radically as well. All in all, refractor telescopes, while giving an excellent image, may be a bit pricey for the first time, or amateur astronomer.
If you are a serious astronomer, then there is little choice, you must have a refractor telescope with an apochromatic correcting lens. However, if you are just starting out and not sure how serious your backyard habit may become, you might want to consider a less expensive reflector telescope for starters at least.