A refractor telescope is a type of optical scope used by both scientists and hobbyists. Essentially, they work by a series of lenses, somewhat like those you’ll find in eyeglasses, that focuses and intensifies light entering through one end. This gives a clear, enlarged image at the eyepiece.
These types of scopes are most commonly used by amateur skygazers to learn and have fun while admiring the beautiful heavens. Because they don’t use mirrors in the way reflecting telescopes do, they don’t require any difficult collimation (alignment) procedures that will prevent images from getting into focus until done correctly.
For this reason, they are great for inexperienced users and many beginners’ scopes are based on the refracting principle. Whatever level of scope you’re interested in, there a few basic parts that can be found in any refractor telescope.
Anatomy of a Telescope
Looking at one of these, the first thing you’ll notice is of course the main scope itself. On top of this is mounted what’s known as the finder, which is just a less powerful telescope that helps you locate the general area of objects in the sky and therefore makes aiming easier. Finally, the stand can be of two varieties.
The most common is a stand that allows the scope to move horizontally and vertically, called an altitude-azimuth or alt-az base. The other kind is known as an equatorial mount, which has to be aligned to the earth’s North Pole. The advantage of this type of scope is that they can track objects across the sky with a simple adjustment. Because the earth rotates, stars and planets will slowly drift out of view; an equatorial mount just makes it easier to adjust for this.
A refractor telescope does have a couple of drawbacks, most of which become more noticeable as the size of the scope increases. For the typical home user, though, the images they see with their refractor should be plenty clear enough, while the simplicity of these scopes is a major point in their favor.
More about how and for what telescopes are used.
Though they mostly manufacture reflecting instead of refracting scopes, this company sells some nice beginner’s telescopes.