Barska AC10552 manual Roof Prism System, ED Extra Low Dispersion Glass, Phase Coating

SPOTTING SCOPE TERMINOLOGY

A spotting scope is an optical instrument that is used for spotting or viewing distant objects such as wildlife or landmarks. It is usually high powered but compact.

PRISM SYSTEM/TYPE

The prism system of a spotting scope reduces the size of a long optical path and correct an inverted image.

Roof Prism System

The prisms overlap and are aligned in a straight line with the lenses allowing to have a slim construction.

Porro Prism System

The objective is offset from the eyepiece offering greater depth perception and a wider field of view.

PRISM GLASS

The common standards of optical prisms are barium-crown (BAK-4) glass or borosilicate (BK-7) glass. The BAK- 4 is a higher quality glass that reduces light scattering, resulting in sharper and brighter images.

OBJECTIVE LENS DIAMETER

The second number in the reference (i.e. 20-60x60) indicates the diameter of the objective lens or the front lens. The larger the objective lens, the better the light transmission, thus the brighter the image.

ED (Extra Low Dispersion) Glass

ED Glass is designed to provide precise optical color correction. It is multi- coated to improve contrast and transmission across the visual spectrum and provides reduced chromatic aberration.

PHASE COATING

A special optical coating that is applied onto the BAK-4 prisms for “phase- correction”. Phase coating results in maximum resolution and optical quality by correcting or “phase shifting” the light that is reflected off the prisms and optimizing it for the scope’s aperture size. Thus reducing internal glare and delivering enhanced contrast and high resolution of details. The results are extreme bright and crisp images, and a true color fidelity.

MAGNIFICATION (POWER)

Magnification is the number of times the object being viewed is enlarged.

2011 BARSKA Sport Optics Catalog

The spotting scope is often identified by two numbers, for example: 20-60x60. The first number indicates the magnification or the power of the scope, expressed by the letter “x”, for times. With this variable zoom power, that

means that the object being viewed appears to be 20 to 60 times closer than would be seen with the naked eye.

OPTICAL COATINGS

Various coating processes on the lenses and prisms will

determine the brightness and the light gathering of a spotting scope, providing higher contrast and brighter images. The types of coating are:

Coated - A single layer on at least one lens surface.

Fully Coated - A single layer on all air-to-glass lens surfaces Multi-Coated- Multiple layers on at least one lens surface. Fully Multi-Coated- Multiple layers on all air-to-glass surfaces.

FOCUS SYSTEM

The mechanism, usually with a turn-adjustable knob, that is used to focus the spotting scope on the object being viewed.

FIELD OF VIEW (F.O.V.)

This is the side-to-side linear measurement of the circular field seen through a spotting scope. It is defined by the width in feet of the area visible at 1000 yards, or in meters at 1000m. The higher the magnification, the narrower the field of view.

CLOSE FOCUS DISTANCE

The closest distance to the observed object that the spotting scope can be used while retaining a sharp focus.

RESOLUTION

The measurement of the scope’s ability to distinguish fine detail and sharpness.

EXIT PUPIL

This refers to the size of the small disc of light that exits a spotting scope. To determine the size, divide the objective lens diameter by the power. For example a 20x60 spotting scope will have an exit pupil of 3mm. (60/20=3)

EYE RELIEF

This is the distance a scope can be held away from the human eye and can still observe the entire field of view. Long Eye Relief (LER) reduces eyestrain and is more comfortable for eyeglass wearers.

WATERPROOF/FOGPROOF

Spotting scopes can be O-ring sealed for complete waterproof protection, and fogproof which means that they are nitrogen-purged to prevent anti-fogging inside the optical surfaces. These models are able to keep completely dry inside after immersion in water.

Spotting Scope Limited Lifetime Warranty

(Within USA and Canada only)

This warranty does not cover consumer-caused damages, abuse, normal wear-and-tear, unauthorized repairs or modifications. For further detailed information, please refer to the warranty policy enclosed with products.

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