A Spotting scope
is an optical instrument used to view distant objects primarily
on land - therefore optimized for terrestrial observations. Most
look and work just like small telescopes
Maksutov, or catadioptric optical design. Normally
50mm to 80mm objective lens and magnification anywhere from 15x to 60x, but there
are more powerful spotting scopes with higher magnification and larger objective
lens to 90mm
scope coated optics:
Coatings on lens surfaces reduce light loss and glare due to reflection, resulting
in a brighter, higher-contrast image with reduced eyestrain. Many spotting scopes
are coated with a microscopic film of magnesium fluoride. More coating leads to
better light transmission. ED (Extra Low Dispersion Glass) in our
scopes provides exceptional color correction and razor sharp images for
serious nature and bird watchers, and it virtually eliminates chromatic
aberration usually seen during planetary and lunar viewing - perfect for
astronomical and terrestrial observations as well! High Quality spotting
scopes feature the best coating available. HD (High Definition) spotting
scope glass helps to eradicate the slightest chromatic zonal aberrations and
contributes to a more faithful color image and normally recommended for
Coated - A single layer on at least one lens.
Fully-Coated - A single layer on all air-to-glass
Multi-Coated - Multiple layers on at least
one lens and all surfaces are coated at least once.
Fully Multi-Coated - Multiple layers on all
The exit pupil refers to the size of the column of light that exits a spotting scope.
The larger the exit pupil, the brighter the image. To determine the size, divide
the objective lens diameter by the power (a 15x45 model has an exit pupil, or useable
light, of 3mm).
The distance a spotting scope can be held away from the eye and still present
the full field of view. Extended or long eye relief reduces eyestrain and is ideal
for eyeglass wearers.
of View (F.O.V.):
Field of view is the side-to-side measurement of the circular viewing field
or subject area. It is defined by the width in feet or meters of the area visible
at 1000 yards or meters. A wide field of view is better for following fast-moving
action or scanning for wildlife. Generally, the higher the magnification, the narrower
the field of view.
A combination optical configuration using lenses and mirrors to create a
total scope length much shorter than the total focal length of the system. This
provides a compact design yielding long focal length performance.
scope magnification (Power):
Spotting scopes are often referred to by two numbers separated by an "x". For example:
15-45x60. The first number is the power or magnification of the spotting scope.
With a 15-45x60 variable power spotting scope, the object being viewed appears to
be 15-45 times closer than you would see it with the unaided eye.:
We always recommend a quality
tripod to hold the
or Close Focus:
The closest you can be to an object and maintain visual clarity.
The second number in the formula: (15-45x60) is the diameter of the objective or
front lens. The larger the objective lens, the more light that enters the spotting
scope, and the brighter the image.
Most optical prisms are made from borosilicate (BK-7) glass or barium crown (BAK-4)
glass. BAK-4 is higher quality glass yielding brighter images and high edge sharpness.
The prism system turns what
would be an upside-down image right-side up.
Roof Prism System - The prisms overlap closely,
allowing the objective lenses to line up directly with the eyepiece. The result
is a slim, streamlined shape in which the lenses and prisms that magnify and
correct the image are in a straight line.
Porro Prism System - The objective or front
lens is offset from the eyepiece. Porro prisms provide greater depth perception
and generally offer a wider field of view.