Sports Optics

Part of the Patrick Moore's Practical Astronomy Series book series (PATRICKMOORE)


Terrestrial telescopes, that is, refractors that give an upright and correctly orientated image at the eyepiece, have enjoyed a long and distinguished history. As we saw in Chap.  1, many of the great refractor builders of yesteryear made a lot of money from the sale and distribution of small, handheld spyglasses for use in military and naval applications, as well as for private, recreational use. The earliest forms were small Galilean refractors or “field glasses,” but their fuzzy views and restricted fields of view limited their use. More sophisticated designs appeared in the eighteenth and nineteenth centuries, featuring doublet and triplet objectives mounted in beautiful brass tubes. The upright image was provided by an additional concave lens placed ahead of the eyepiece. Indeed, instruments were made that allowed the concave element to slide out of the draw tube for purely astronomical (upside down) purposes. More than any other telescope genre, surveying the spotting telescope market is like hitting a moving target. There are a staggering number of different models available to the consumer, and so it’s well nigh impossible to cover each and every instrument. Luckily, many of these refractors can be classified on the basis of their overall design – traditional models that employ prismatic arrays and deliver an eyepiece image (such as binoculars), and what can be called “crossover” telescopes, which are small, short focal length achromatic or ED doublets, originally marketed to star gazers but now enthusiastically endorsed by birders and other outdoor hobbyists. Before delving into the details of particular models, let’s make note of some general points about daylight observing.


Color Correction Draw Tube Angle Body Exit Pupil Porro Prism 

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  1. 1.GlasgowUK

Personalised recommendations