Step 1: With right eye closed, rotate the central focus knob until image in left eyepiece is clear and sharp.

Step 2: With left eye closed, rotate the independent right diopter knob until the image is clear and sharp.

Step 3: Look with both eyes and image should be very crisp and in focus. If not, repeat above steps.

Fully multi-coated means that every optical surface has an anti-reflective (AR) multi-coating to maximize light transmission.  

Light transmission is the resulting light that gets to your eye from the object. Typically, some light is lost due to reflections from the optics so there is always some loss of incoming light, even with the best anti-reflective coatings. Carson is known for binoculars with high light transmission at affordable prices.

Chromatic aberration, also known as color error, is caused by dispersion, where light spreads out according to its wavelength like a rainbow. This effect also happens in a lens, so different lens materials or designs can reduce chromatic aberration. Chromatic aberration is typically seen as purple fringing on the edge of a dark object on a light background or lack of contrast in a color image.

Dispersion occurs when the colors of light spread out due to different wavelengths. Think of a rainbow: this is what dispersion looks like. White light is the combination of all colors; when reflected off something like a water droplet or a lens, the various colors will spread out differently.

Dielectric coatings are a type of reflective coating. They are one of the best grades of coatings available to maximize light transmission.

BAK4 is a higher-grade prism glass than BK7, but the glass type does not have a critical difference on overall performance.

Relative brightness is the exit pupil diameter squared. For example, an 8×42 binocular with an exit pupil of 5.25mm has a relative brightness of 27.6, while a 10×32 binocular with an exit pupil of 3.2mm has a relative brightness of 10.2.

Twilight factor is the number used to calculate the relative effectiveness of binoculars in low light situations, such as hunting at dusk. You can calculate the twilight factor by taking the square root of the total magnification and multiplying it by the objective lens diameter. For example, the twilight factor of an 8×42 binocular is 18.3.

Most are made of plastic (like polycarbonate), aluminum or magnesium. The different materials have different costs, strengths and weights. Plastic would be the lightest and least expensive. Aluminum is more expensive and heavier than plastic. Magnesium would be the most expensive of the three, but it’s also a lightweight material.

There are various levels of waterproofing, such as water resistant, splashproof, waterproof, etc. Waterproofing levels are usually stated in IPX ratings, with a higher number relating to a higher level of protection.  

Fogproof means the internal surfaces of the binoculars won’t fog. This doesn’t apply to external surfaces. Typically, the binoculars are pumped with an inert gas and sealed to prevent internal fogging. For external fogproofing, you could apply a safe fogproof solution or wipe to the lens surface to remove the fog. Do not rub your lenses with dry clothes or paper towels as you may scratch or damage the optics.

Field of view (FOV) is the degree of the angle of the visible field seen through binoculars. Although the FOV specifications may seem limited, it’s the apparent field of view (AFOV) that will dictate view perception, giving you a larger viewable angle. For example, a binocular with a field of view of 7 degrees may appear to have an apparent field of view of 50 degrees when you see the magnified image.

An antireflective or anti-reflection (AR) coating is a type of optical coating applied to the surface of lenses and other optical elements to reduce reflection. Without anti-reflective (AR) coatings, there would be a significant reduction in the amount of overall light transmission, which would result in a darker image.

On a roof prism, the image is split into the two roof parts of the prism. Because of the split, a phase shift error occurs between the images. When the two halves of the image recombine, there can be some loss of contrast in the image. In high quality binoculars, a phase corrective coating is placed on the prism to minimize this error, thereby increasing the contrast for roof prism binoculars.

ED glass stands for Extra-low Dispersion. Dispersion occurs when colors spread out due to the wavelength, like a rainbow effect. Since this also occurs in lens systems, some lens elements can be made from ED glass to minimize the dispersion and resulting chromatic aberration (color distortion that creates an outline of unwanted color along the edges of objects – caused by a failure of a lens to focus all colors to the same point).

Yes, binoculars can be mounted to a tripod with a binocular tripod adapter. This is great for stability over long hours and highly recommended for digiscoping.

Close focus or minimum focus distance is the closest/minimal distance that a pair of binoculars can focus on. The shorter the close focus distance, the more one can focus on details that are typically not visible to the naked eye. 

Porro prism binoculars have a prism design that results in a binocular tube with a bend, so there is not a straight line between the eyepiece and objective lenses. These binoculars can provide greater depth of field and a wider field of view compared to similar roof prism models.

Roof prism binoculars use two roof prisms, resulting in an instrument with parallel sides and objective lenses that are the same distance apart as the eyepiece. A roof prism binocular has straight barrels, so it’s more compact and easier to hold.

To calculate the exit pupil diameter, divide the diameter of the objective lens by the magnification of the binocular. For example, a 10×32 binocular has an exit pupil of 3.2 millimeters. All binoculars with the same magnification and objective lens size have the same exit pupil diameter.

The exit pupil is a bright circle that can be seen in the center of each eyepiece when you hold binoculars about 30cm (arm’s length) from your eyes with the objective lenses pointed toward a bright light. The diameter of the bright circle helps determine how much light will reach your eye. To determine the exit, divide the diameter of the objective lens by the magnification of the binocular. For example, a 10×32 binocular has an exit pupil of 3.2 millimeters. All binoculars with the same magnification and objective lens size have the same exit pupil diameter. Your pupils will adjust to the amount of light outside, whether low or bright light. A binocular that has a larger exit pupil can make your viewing field brighter, which is important to consider when using binoculars in dark situations or for astronomical observation.

The diopter knob allows you to balance any vision differences between your left eye and right eye. The first time you use any binocular, always make sure to properly adjust the diopter knob. There may be a mark for the zero-adjustment point, so you can use that as a reference.

Eye cups typically twist up or fold down. If you don’t wear glasses, the eyecups should be twisted up to their fully extended position. If you do wear glasses, keep them folded down. This is critical. It will keep your eye at the proper eye relief distance from the binocular’s optics, which will provide the best image and maximum field of view.

The objective is the lens system farthest from where you put your eye, where the incoming light from the viewed object first enters.

The eyepiece is the lens system closest to where you put your eye.

The bridge of binocular is the space between the two barrels. Some binoculars have an open hinge bridge design, and some have a closed bridge design, which is basically a larger, single-piece hinge. Open hinge systems use two smaller parts of the bridge, so they’re typically lighter but may not be as durable. Closed bridges are very rugged but heavier.

Yes, you can view the moon with 10x or 12x binoculars, the larger the objective the better. Typically, we would recommend one of our 12×50 binoculars, which you can mount onto a tripod with a binocular tripod adapter.

The higher the power, the harder it is to quickly find and follow movement. Higher power binoculars make spotting and following birds more difficult.

Typically, 8x is ideal for bird watching.

A lot of factors influence binocular cost, including size or aperture, magnification, type of prisms, types and quality of coatings, body material, lens design and quality. Overall, optical quality is usually the main difference. In an inexpensive, low-quality binocular, the image is very small and dark, could be hard to focus, and only crisp near the middle of the image. In an expensive, high-quality binocular, the image is large and bright, easy to focus, and has a crisp, high-resolution image.

Lower power is better because it’s hard to quickly find and follow movements if you are at a high magnification. Ideal magnification would be 6x-8x for most events. For opera, binoculars are called opera glasses, and they are typically 4-6x.

This age-old question really comes down to personal preference. Do you want to carry heavy, bulky binoculars from your car to the stadium? Do you prefer the added brightness that a full-sized binocular will offer? Or is the convenience of putting the binoculars in your jacket pocket more important to you? The jury is split between full-sized binocular brightness and compact binocular portability. Whether you choose compact or full-sized binoculars, there are a few other factors to consider. If you are watching a fast-moving sporting event, do not opt for binoculars that are too powerful (8x magnification is ideal). Higher magnification means a smaller field of view, so it will be harder to follow the action. Also, make certain that the optical configuration of the binoculars offers a sufficiently wide field of view. Keep in mind, however, that you may sacrifice binocular edge definition or binocular eye relief with a wide field of view. In conclusion, it is important to compare every feature a binocular offers before you make your decision.

The magnification of a binocular describes how many times closer an object appears through the binocular than with the naked eye. An 8×21 mm binocular magnifies the image to eight times its normal size. Typical binocular magnifications range from powers of 7x to 10x; however, they are also available in much higher magnifications. Keep in mind that binoculars with higher power gather less light, and the viewing field will be reduced, as well. It is also very difficult to keep an image steady at very high magnifications using a handheld binocular. A tripod is usually necessary to steady an image at higher magnifications.

There are many factors to consider in choosing the right binocular for an individual’s needs, including price, color, and style. The most important factor in this decision relates to how you intend to use the binoculars. To most people, binoculars are a simple optical device, but in reality they are complex and precise optical instruments.

The amount of light passing through the different lenses of the binocular depends on the diameter of those lenses. The objective lenses are located at the front of the binocular. The diameter of the objective lenses is measured in millimeters. An 8×21 mm binocular has an objective lens diameter of 21 millimeters. The larger the diameter of the lens, the more light they will gather. More light means a brighter image of greater detail and clarity. The size of the binocular’s exit pupil also affects the brightness of an image. The exit pupil is the diameter of the beam of light, in millimeters, that passes through the binocular’s eyepieces (or oculars). The larger the exit pupil, the brighter the binocular image becomes. Keep in mind, however, that larger binocular lenses means larger binoculars.

The field of view is the size of the area that can be viewed through the binoculars. Field of view is measured in two ways: angular field of view and linear field of view. The angular field of view of a binocular is measured in degrees. Linear field of view is the width of the area, in feet, that is visible at one thousand yards. Remember that the higher the power of your binocular, the smaller the field of view will be. In most cases, the larger the field of view is, the more the image clarity will decrease, especially around the edges. Bear this in mind when making your choice. Bigger does not always mean better!

There are prisms located inside binoculars that function to flip an inverted image upright. There are two common styles of prisms used in binoculars: the BK-7 and the BAK-4. The BAK-4 prism is made of a higher-density glass and can produce sharper images than a BK-7 prism can. If you are unsure as to which prism is being used, hold the binoculars out in front of you and look through the eyepiece. If you see a square shaped beam of light, chances are a BK-7 prism is being used. A round beam of light indicates the use of a BAK-4 prism.

All the optical components of binoculars (lenses and prisms) should be coated to minimize light loss and reflection problems inside the binocular. A poorly-coated binocular can lose up to 50% of the light initially gathered through the objective lens, resulting in a poor quality image. By coating the optical components with a fine film of chemicals, light loss can be greatly decreased. The highest quality binoculars have multiple coatings on all the optical components. These are known as “fully multi-coated” binoculars. These binoculars have the least loss of light and the result is a higher quality image.

There are several steps you should take to focus your binoculars. The first step is to close your right eye and look through the left eyepiece of the binocular. Turn the center focusing wheel until you see a sharp image. Then, close your left eye and look through the right eyepiece. Turn the diopter eyepiece until you see a sharp image in your right eye. Lastly, look through both eyepieces. Use the center focusing wheel only to correct the focus when you begin looking at different objects. Now you are ready to fully enjoy your binoculars.

Eye relief is the distance, in millimeters, that a binocular can be held away from the eye and still see the entire field of view. If you wear glasses, a longer eye relief would be advantageous since the glasses prevent your eyes from getting as close to the eyepiece as possible.

Make sure your lenses are clean at all times and keep them free of fingerprints, dirt, and debris. Use a Stuff-It microfiber lens cloth or a C6 Lens Cleaner to clean your lenses quickly and safely. Never use chemicals on your lenses; it can harm the optical coating. When not in use, always replace the lens caps and store your binoculars in a case. For more cleaning options, visit the Lens and Screen Care section of our website.

8×42 mm binoculars are the most popular optical configuration for bird watching. A 42 mm objective lens provides sufficient light gathering capabilities in low light conditions, and an 8x magnification allows the user to “steady” the binoculars much more readily than with higher powers, making the task of bird-identification a little easier. Look for 8×42 mm binoculars with high light transmission capabilities like our 3D/ED Series.

Some informal industry surveys suggest that 40% of all binoculars that are sold in the United States are sold to hunters. The most popular style of binoculars sold are 10×42 mm. What is so special about 10×42 mm binoculars? Deer are most active at dawn or dusk, so brightness is critical. Full-sized 10×42 mm binoculars gather more light than their compact counterparts, so 10×42 mm binoculars are an obvious choice.