Search for information on this site.

Anodizing - a cosmetic finish that is applied to the outer tube of scopes to provide a protective barrier from scratching or corroding. Often available in gloss or matte options.

Armor coating - a special "rubber-like" finish that is applied to binoculars and spotting scopes. Waterproof and quiet, armor coating provides superior protection of the optical system from the elements.

Diopter - a unit of measurement for the power of a lens or optical system, often associated with binoculars.

Eye Relief - the distance that optical instruments can be held away from the eye and still allow the user to see the subject through the eyepiece. Handgun and shotgun scopes have extended eye reliefs as compared to most rifle scopes.

Exit Pupil - describes the image projected to a point beyond the eyepiece, where your eye must be positioned to clearly see the entire image. For maximum clarity, the exit pupil diameter must be equal to or greater than the diameter of your pupils - usually 2mm to 7mm. To determine exit pupil diameter, divide the objective lens by the power rating.

Field of View - the size of the area that you see when looking through a scope or pair of binocular, usually measured in feet at one thousand yards.

Internal adjustment graduation - distance the point-of-impact will move with each "click" of either the elevation or windage adjustment. Each "click" on most Redfield scopes will move the point of impact 1/4" at 100 yards.

Lens Coatings - used to increase even light transmissions, contrast and sharpness in optical lenses (often aluminum oxide, magnesium fluoride, barium, lanthanum, etc). Designated in degrees of quality (coated, fully coated, fully multi-coated). Fully multi-coated lenses provide multiple coatings on all air to glass surfaces, promoting the brightest, clearest images possible.

Minute of Angle - the measurement of the field of view expressed in degrees.

Nitrogen - used in scopes to create a moisture-free environment which prohibits condensation or fogging within the scope.

Non-magnifying Reticle - the position of the reticle in the second focal plane, which eliminates magnification of the reticle.

Objective - the forward lens system on a scope, or the two front lenses on a binocular. Generally measured in millimeters (mm).

Parallax - the condition when the image does not focus exactly on the reticle plane.

Power - also called magnification. This is the amount of enlargement of the target compared to the human eye. For example, a fixed power (7X) scope will magnify the target seven times compared with the naked eye. Variable power scopes (3X-9X) offer the ability to change power settings to shooting conditions.

Refraction - the change of direction of a light ray as it passes from one lens to another.

Roof Prism - lighter in weight and more compact than porro prism designs. Used to invert the image as it passes through the optical system of a pair of binocular, creating the necessary magnification.

Rotary Dovetail - a mounting system designed to attach and align a handgun or riflescope, and to allow for optimum precision.
 

Copyright © 1997, 1998 Redfield, Inc.
Site designed and maintained by Outdoor Management Network Inc.
See also Redfield information on