a numerical designation used in describing the
power of binoculars. Binoculars are used to observe objects which, to the naked eye, are far away but when seen through the binoculars appear closer. Binoculars consist of two small telescopes with a separate viewing
tube for each eye. The tubes are mounted with hinges to a
single frame to allow the eyepieces to be moved closer together or further apart (since the distance between the eyes varies from person to person). In the numerical designation 7X50, the first figure (7) gives the
actual magnification (the apparent enlargement of objects seen through a lens) of that being viewed. For
example, if an
object appears to be one inch high with the naked eye, it would appear 7 inches high when viewed with 7X50 binoculars. The
second figure (50) gives the diameter (the distance of a
line passing from one side of a circle through the center to the other side) of the binocular lens in millimeters. Binoculars of this magnification (7X50) can be used for viewing such things as ships at
sea, whereas binoculars with lower magnifications would be used for viewing things at a closer distance such as
bird watching, sports, etc.
Example Even though I was in the very last
row at the opera, the actors looked huge thanks to my 7X50 binoculars! So anyway, it just goes on at this
mad rate, and at the end of it, finally concludes, without any preamble of any kind whatsoever, that a yachtsman
needs a 7X50
type pair of binoculars-an
authoritative conclusion based on all of the optical
formulas.