Friday, December 02, 2005

Lidl Online

Lidl Online: "Bresser kikkert 10x50

Kvalitetskikkert med Bresser optik, gummiarmering, Bak 4 porro prismer og nedb?jelige ?jekopper, der giver brilleb?rere fuldt synsfelt.

binoculars: Information From "The conventional way to describe binoculars is to use two numbers separated by 'x', for example '7x49'.

The first number is the magnifying power, the second the diameter of the objective lens (the one further from the eye) in millimeters.

Binoculars range from small 3x10 models, often used in theaters,
to average 7x50 or 10x50 for amateur outdoor use,

to large 20x80 or even 20x140 'galaxy' models.

The largest models are actually powerful telescopes, and their high magnifying power means that a static mounting is necessary for their use, since otherwise natural small hand movements would be amplified too much.

A practical limit on standard hand-held binoculars can be put at 9x or 10x."
For example, a 10x50 binocular produces a 5 mm exit pupil (objective size divided by the magnifying power).
For maximum efficiency, this image should match the diameter of the eye's pupil, which in dark environments grows to about 7mm.
This ratio is also a measure of the brightness of the image, the larger the exit pupil, the brighter the image reaching the eye.

Thus, 10x50 and 8x40 binoculars have the same brightness, although the latter has a smaller magnification.
An exit pupil larger than the diameter of the user's eye pupil wastes light.


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