Types of Telescopes
Telescopes come in a wide variety of different types but they all either use a lens to focus the light, or a concave mirror. The first type of scope is commonly referred to as a refracting telescope (as the light is refracted into focus) whereas the telescopes with mirrors are referred to as reflecting telescopes.
Most people associate a telescope with the first type, probably because it is the simplest form of scope. It usually comes in only one configuration, making it easy to recognise.
Reflecting telescopes come in many different shapes and configurations and you will find that the biggest telescopes are always of this type. They are not only more compact, they tend to provide more aperture for the same price.
Binoculars
Binoculars are a very useful piece of equipment for the astronomer. They provide great wide field images at low magnification and allow you to learn to find your way around the stars much more easily than with higher magnification telescopes.
Binoculars are, as the word suggests, two oculars or two eyepieces. A binocular is really two refracting telescopes fitted together so that you can use both eyes to look at distant objects at the same time. Binoculars incorporate a number of prisms for three purposes: Firstly, to put the picture upright again (because binoculars are usually used for terrestrial viewing). Secondly, the prisms are used to reduce the length of the tubes in order to make them easier to handle. Lastly, the prisms make it possible to reduce the width between the eyepieces in order to be able to look through them with both eyes.
Binoculars usually do not allow you to interchange eyepieces. They don't normally incorporate a mount either, although some of the larger apertures may be fitted with photo tripod adapters. Big binos are heavy and difficult to hold up to your eyes for long periods.
