Just in case you're confused by all the jargon and industry speak about binoculars the following has been provided courtesy of Carl Zeiss.
Magnification
In simplest terms, magnification is a measure of how many times better
you can see an object through your binoculars than with your naked eye.
In the standard specifications for a binocular model, magnification is
reflected by the first number you see.
Objective Lens Diameter
The objective lenses are the front lenses. The diameter of the objective
lens is expressed in millimeters. As with the aperture of a camera
lens, the size of objective lenses determines the amount of light that
can enter your binoculars.
It combines with magnification, exit pupil, type of coating and type of
prism to determine overall light transmission efficiency.
Field of View
Avid binocular users pay attention to this critical performance factor,
because field-of-view is the actual width of the sight picture provided
by your binoculars at a specific distance. Field-of-view is determined
by magnification and the focal lengths of the objective and eyepiece
lenses. But one thing is always true: More magnification means less
field-of-view.
Field-of-view may also be expressed in degrees, which is called the
angular field. To convert angular field to the more practical linear
field, multiply the angular field by 52.5.
Twilight Performance
Using the below formulas gives a basic evaluation of low light
performance, however, one must keep in mind that they are mathematical
formulas and do not take into effect some of the most critical features
in optics; glass quality, number of lenses, precision of manufacturing
and coatings.
Height
If you could line-up every ZEISS binocular and monocular model on a
table, with the objective lenses down, you'd see an array of heights.
ZEISS models range from 2.6 inches to 11 inches. Height is a function of
mechanical and optical design.
Width
As with eyeglasses, binoculars must fit the width of the user's eyes to
be effective. The natural accommodation was to design sturdy hinge
systems that allow you to adjust for your particular Interpupillary
Distance (ID), which is the center-to-center distance between your
pupils.
When examining the overall width of binocular models, it is necessary to
establish a base line ID as a standard position. All ZEISS binocular
width measurements, therefore, are based on an ID of 65mm.
Weight
The weight of a given pair of binoculars is influenced by several key
factors: the type of glass, the diameter of the objective lens, the type
of prism system, the volume of the prism system, the material used in
the housing, the volume of the housing, and the basic design style.
ZEISS manufactures a wide range of weights, from a 20x binocular that
weighs about 58 oz. to 5x monocular that comes in at just .08 oz.
Careful consideration should be given to choosing the best weight for
your purposes. Today, virtually all binoculars are substantially lighter
than their counterparts from a decade ago.
Exit Pupil
This is one measure -- expressed in millimeters -- of the amount of light that reaches your shooting eye.
Exit pupil also describes the image that's projected to a particular
point in space. Your eyes must be positioned at that exact spot in order
for you to see the full field-of-view with maximum resolution. When
holding the binoculars at arm's length, it's the small, circular image
that's visible in each eyepiece lens. When your eyes are in the proper
viewing position, the round shafts of light combine to create a fully
detailed sight picture.
By the way, the average adult eye dilates to a maximum of 7mm in extreme
low light conditions. For binoculars to deliver their full light
gathering capability, the exit pupil must be equal to, or greater than
the diameter of your pupil at any given moment.
Interpupillary Distance
The center-to-center distance between an adult person's eyes averages
between 58 to 72mm, and is described as the Interpupillary Distance
(PD). The binocular should be capable of any setting between those two
measurements. When the user makes this adjustment correctly, the sight
picture forms a single round circle. When it's slightly out of
adjustment you can see two distinct circles, as it is often depicted in
the movies. This is corrected by folding in or separating the barrels of
the binocular. All binoculars are hinged at the center for this
purpose.
Generally speaking, roof prism binoculars have a smaller range of hinge adjustment than do porro prism binoculars.
Focusing Range
All binoculars have the ability to be focused for infinity. So a primary
point of distinction between binocular models is the minimum focus
range. Birders tend to favor models with a short focus range of about 15
feet, but 20 to 25 feet is usually acceptable.
The concept of shortest focusing distance is a theoretical one based on
the visual acuity of a young person. Older people have slightly more
distant near focus. Throughout the population, there is a wide variance
of near focus distances from person to person. Also, eyeglass wearers
who remove their glasses will notice changes in their normal short focus
distance.
Advanced Optics System (AOS)
An abbreviation for Advanced Optics System, this is ZEISS' proprietary
new optical design for binoculars which increases optical performance
while reducing weight and bulk. At the heart of this revolutionary
approach are new glass materials that contain neither lead nor arsenic,
so production is environmentally friendly. Lenses in this system are
thinner at the center, which lowers overall weight.
Prisms
Erecting prisms are used in binoculars to correct for an inverted image.
There are two basic types: Porro Prisms, which give traditional
binoculars their classic two-stage profile, and Roof Prisms, which
produce straight optical channels. Of the Roof Prisms, ZEISS' Abbe-König
offers the highest light transfer.
Many people believe that Porros have superior optical qualities. But
Roof Prism models, such as those manufactured by ZEISS, use phase
coating techniques to produce truly remarkable image quality.
Stray Light
When light entering the binoculars reflects off of
interior surfaces, the reflected light eventually exits inside the
binoculars in the form of stray light. This unfocused light typically
diminishes the image quality of the sight picture.
To limit the detrimental effects of stray light, ZEISS employs the proprietary anti-reflective lens coatings known as T* and MC. Another ZEISS-exclusive
coating is the P* Phase Correction Coating which is applied to roof
prisms. In addition to these coatings, interior surfaces and prism
housings are anodized in a matte black finish to eliminate the
reflection of stray light.
Coatings
As light strikes an air-to-glass surface, a small percentage of light is
reflected away and does not transfer through to the eye. This effect is
limited when these glass surfaces are treated with a microscopic layer
of refractive material, such as magnesium fluoride.
To achieve multicoating, several such refractive layers are applied.
When properly applied, coatings can dramatically enhance light
transmission properties by delivering more of the available light to the
eyes. Zeiss' two proprietary anti-reflective coatings are called T* and
MC multicoating. An additional Zeiss-exclusive coating, P* Phase
Correction Coating, is applied to Roof Prisms to correct color fringing.
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Top Right Half:
T* multilayer coating: superb transmission, image brightness, brilliance and colour fidelity, rich contrast.
Bottom Left Half:
Poor contrast and low transmission. |
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Waterproof
There is no standard in the United States for Waterproof but all Carl
Zeiss Sports Optics are tested against German DIN ISO 14135 and ISO
9022-8 Standards. This standard tests for fogging and moisture in
various environments including submersion in water. ZEISS' excellence
in design ensures precision and tight fittings. Some products are
filled with Nitrogen for added resistance to condensation and fogging.
All ZEISS products are guaranteed to be water and fog proof and are covered by the industry leading warranty.
