A spotting scope is a type of telescope which is designed to view objects on Earth. Birdwatchers often use spotting scopes in the field to get a close-up view of distant targets, and plane spotters often employ spotting scopes as well. The magnification range for a spotting scope varies, with most falling between binoculars and astronomy telescopes in terms of magnification ability. Many optical supply and birdwatching stores sell spotting scopes, along with accessories like tripods and camera mounts.
Depending on the type of scope, a spotting scope may be rated anywhere between 20 times and 60 times magnification. The higher the magnification, the more useful the spotting scope will be in the field, although extremely high magnification can make a spotting scope difficult to use. Below 20 times magnification, one might as well purchase a set of binoculars. A spotting scope is also designed specifically to have a wide field of view which makes it easy to spot objects in the visual field, and these scopes are also designed to stand up to rugged use in the great outdoors.
A good spotting scope is extremely lightweight, making it easy to carry in the field. Most designers also create weather resistant scopes so that these optical tools can be used in inclement weather. Many scopes also have mounts for telescopes, and some have the ability to interface with cameras so that people can photograph the things they look at. Cameras are highly useful for birdwatchers who might want to supplement their life lists with photographs.
There are two basic types of spotting scope optics. The first is a refractor scope, which uses an optical glass to bend light. Refractor scopes tend to be lightweight, generally less expensive, and very durable. Catadioptric scopes, on the other hand, use mirrors to reflect light to create an image; these scopes are more fragile, but they also create clearer images. A catadioptric spotting scope will also generally be more expensive.
Numerous variations on the basic spotting scope design are available. Some are hinged, for example, allowing the scope to be mounted on an tripod while the viewing aperture can be moved for the convenience of taller or shorter people. Straight scopes have no flexibility, although they can be easier to use when someone wants to track something in their visual field. There are also numerous choices in terms of the focusing mechanism, weather protection, and other features on spotting scopes.