Spotting scope

A spotting scope is a portable telescope, optimized for the observation of terrestrial objects. The magnification[?] of a spotting scope is typically on the order of 20X to 30X. Other common features include:

• somewhat "rugged" or rubber-armoured design
• convenient mounting for attaching to a tripod
• ergonomically-designed and located knob for focus control
• tethered elastomeric lens cap
• a range of eyepieces to give different magnifications, or a variable "zoom" eyepiece to give a range of magnifications, eg 20-60X

The light gathering power of a spotting scope is decided by the width of the objective lens, typically 55-80mmm. the larger the objective, the more expensive the telescope.

The choice of the eyepiece lens determines the overall magnification. The best magnification is decided by a number of factors.

A magnification less than 20x is pointless, since binoculars would do. If more than 60x, the brightness is poorer, and, even on a tripod, shake can be a problem. The field of view is also limited.

Ususally for birding, 20x or 30x is favoured. This gives a good field of view and a bright image.