Binocular Terms

This binocular term is known as the objective lens. It's the second number represented in the label of the binocular size. The aperture is always measured in millimeters. To identify the aperature in the label, it's the 56 in a 8x56 Binocular.

The binocular term Depth of Field is the portion of the image between the foreground and background that appears sharp when the binoculars are in focus. If your on a hunting trip and scanning for deer, you'll want a wider depth of field. The opposite will go for viewing objects up close so you'll need a smaller depth.

The meaning of Digital Camera Binoculars are binoculars that combines both binoculars and digital camera that's built-in. This will allow you to take pictures and watch birds simontaneously.

Most optical users who buy binoculars have one eye stronger than the other. The diopter adjustment feature solves this problem in which it allows you to change the focus of the eyepiece so that the left eye matches the right eye. For better understanding of this binocular term, see the Binocular Diopter Adjustment section in the guide to purchasing binoculars.

The definition of exit pupil is the opening at the center of each lens in which light rays enter and exit. To measure the exit pupil, simply divide the objective lens by the magnification. For example, an Zeiss Conquest 8x40 binocular would have a exit pupil of (40 / 8) = 5. The higher the exit pupil, the brighter the images appear in low light conditions. Night Vision Binoculars will have higher exit pupils and daytime binoculars will have smaller one exit pupils. The reason is a humans exit pupil dialates at different sizes depending on the light conditions. For better understanding of this binocular term, refer to our Binocular Exit Pupil section in the Binocular Buying Guide.

The eye relief is the distance between the lens and your eyes. If you wear eyeglasses, you'll want a larger eye relief. To calculate which size is best for you and for better understanding of this binocular term, refer to our Binocular Eye Relief section in the binocular education guide.

The eyecups are usually made of rubber and allow for comfortable positioning of the eyes during observation. If you wear eyeglasses, make sure the eyecups are folded down. Some binoculars have twist up or pop & lock eyecups which are user friendly because they're more adjustable.

The Field Glass definition is a binocular thats replaced a set of prisms with a second lens to magnify an object. The magnification in field glass binoculars are more durable than prism binoculars but usually max out at around 5x.

The field of view is the distance from left to right when looking through binoculars. For better understanding of this binocular term, see the Binocular Field of View example in our helpful guide to buying binoculars.

The Image Stabilizing Binoculars offer a built-in self steadying device that allows you to hold the image still. This is an exceptional optical feature when using your binoculars in a boat due to the waves forcing the boat to rock up in down. Also, you don't have to worry about having shaky hands because this feature allows you to keep the image steady.

With individual focus binoculars, you're required to focus both eyepieces in order to recieve the perfect image. For better understanding of the definition individual focus and the different types of focus, please refer to the Binocular Focusing section in our buying guide.

The term Light Transmission is the percentage of light that passes through your binoculars. The light transmission depends on the quality of the lens coating. The better the quality, the brighter and sharper the image will appear. For better understanding of the lens coatings that are available, look at the Binocular Lens Coatings section in our purchasing guide.

The size of the objective lens determines the ability of the binoculars to gather light.

The binocular Magnification is the actual power of the binoculars that represents how many times the image is magnified than to the naked eye. To learn more about the binocular term Magnification, view the Binocular Magnification section in our binocular education guide .

The air inside the binoculars are replaced with nitrogen to make them Fogproof Binoculars.

Night Vision Binoculars make it possible to see images in low light conditions and in 100% darkness. These are great for nighttime hunting and supported by both military and law enforcement for surveillance.

The Objective Lens allows light to travel through the binoculars to make the image appear brighter and sharper. Choose your objective lens size carefully. For better understanding of how to choose the correct size, read the Binocular Objective Lens section in the SportsManGuys.com Binocular Shopping Guide.

The O-Rings are considered a special sealant that's applied to the binoculars in order to make the binoculars waterproof.

Phase Corrections means the coating that's applied to a roof prism binocular so that it prevents light from splitting into two beams. It also reduces image contrast.

Porro Prism Binoculars have internal offset prisms in which the light bends inside the binocular tubes to produce an image. To learn more about the binocular term Porro Prism, read the Binocular Prisms section in our helpful guide.

The Range finder is an optical device that combines both binoculars and a laser rangerfinder to form Rangefinder Binoculars. This feature will measure the exact range when focusing on an object. The rangefinding binocular is loved by hunters and golfers because it allows them to measure the distance to their targets and gives them an accurate shot.

Roof Prism Binoculars have internal prisms that are aligned straight to produce a rugged, easy focusing, and quality performing optical device. To learn more about the binocular term roof prisms, check out our Binocular Prisms section in the SportsManGuys.com Binocular Education Guide.

Depending on your activity, The Twilight Factor can have a impact on the resolution of an image. The twilight factor is mostly used for astronomy. It's calculated by multiplying the objective lens size by the magnigication, then taking the square root of that number. For better understanding of the binocular term Twilight, look at the Binocular Twilight section in the SportsManGuys.com helpful section.

Waterproof Binoculars are protected from damage against water or moisture leaking into the binoculars.

Wide Angle Binoculars are binoculars that have a wider field of view. Usually any binocular with a field of view over 400 yards is defined as a wide angle binocular.

Zoom Binoculars have variable magnifications. To identify a pair of zoom binoculars, the binoculars will be labeled 10-22x50. The 10-22x is the zoom.