Binoculars Buying Guide and
Night Vision Guide

A Simple Guide To Buying Binoculars ( Read First ...! ) What Are Binoculars and How Do They Work ? What do the numbers mean? Which Binoculars are right for me ? What does " Exit Pupil " mean ? What Lens Size Should I Buy? What is a BAK-4 Prism? What does field-of-view mean? What are lens coatings? How Do Night Vision Devices Work? If you still have questions Ask the Experts
Quick Chart Equine Sports and Stadium Sports 4x21, 8x25 & 10x25 Xtra-Wide Angle, All 7x35, 10x50 & 12x50, Any Zoom, Compacts from 7x to 10x Boating Any Waterproof Model with A Large Objective Diameter and RubberArmor, 7x50, 7x42, 8x42 & 10x42 Concerts/Theater 5x25 & 8x25 Xtra-Wide Angle, 4x30, 7x18 & 7x21 Compacts, Any Zoom or Wide Angle Model Outdoor/Nature Any 7x35, 7x50, 8x42 & 10x42 Standard Size, 8x30 & 10x30 Compacts, Waterproof Models for Camping General Use/Vacation/Hiking 7x35, 8x42, 10x42 & 10x50, Most Compact and Wide Angle Models Hunting All Rubber Armored, Waterproof and Fogproof Models, 7x to 10x Power Models for General Hunting, 12x or 16x for Distant Game/Varmints, Compacts fit in a Pocket for Hunters on the Move Birdwatching 8x42 is the standard, 10x42, 10x50 & 12x50 for Details in Smaller Species at a Distance, Compacts with a 30mm or Greater Objective Lens size, Any Binocular with Long Eye Relief and Good Close Focusing Ability Low Light 7x50 (Best Light-Gathering), 8x42, 10x50

What Are Binoculars and How Do They Work ?

Binoculars, in its simplest definition are magnification instruments that are made up of two telescopes mounted on a metal or plastic frame so that a viewer can view images as if they were much closer.

The process by which this is done is utilizing curved glass lenses and multiple lenses within the frame to magnify the subject each time it passes through to the next lens. The downside to this is that each time this occurs some light is lost. More often than not prizms are utilized in the process as well which bend and reflect the light entering the objective lens.

Many binoculars today utilize prizms which bend the light as it enters the objective lens and helps to magnify the image as it passes through the frame. The result is a binocular that can be made smaller and more powerful.

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What do the numbers mean?

Binoculars are often specified by a set of numbers such as 7×35 or 8×40, the first number indicates the strength of magnification (how many times closer the subject is to you, 5 times closer, 7 times closer, 10 times closer) and the second number is the size of the objective lens measured in millimeters going across the lens. The size of the objective lens will determine how much light it can obtain for effective viewing. The higher the number, the larger the lens; in effect allowing more light to pass through thereby projecting a brighter image and viewing experience.

Zoom Binoculars work on the same principle as regular binoculars except that the power can be adjusted to give you varying ranges of magnification. For example, a binocular that is listed as 10-22x50mm means the zoom portion is capable of viewing at 10x power minimum and can be adjusted up to 22x power and the 50mm would be the objective lens size ( the larger lenses at the opposite end of the binocular ). When considering zoom binoculars remember that a larger objective lens would fair better giving you the greatest amount of light gathering, however they will be bigger and heaver also.

Binoculars are built around a frame that houses the two telescopes and is generally hinged to allow for adjustment for each individual viewer. Some binoculars are perma focus and never need adjustment, just pick up and use them. While others have a focusing wheel in the center to allow for manual focusing and a greater degree of fine tuning for sharper images. Some models also offer focusing systems on each eye piece and once adjusted they are set for that viewer. Separate focusing of each eyepiece ( known as Diopter Control ) is also available in some types of binoculars, which allows for additional precision.

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Which Binoculars are right for me ?

Remember one thing, the higher the magnification the steadier your arms need to be. If you consider anything over 12x magnification you may want to invest in a stand or tripod that will hold the binoculars for you. Generally speaking though, 7x - 12x magnification should be fine for wide area viewing and handholding.

The most important things to consider are:

Once these answers become evident it becomes much easier to narrow down the particular models to 2 or 3 and then the choice becomes one of personal preference.

Here is an example of a question asked by one of our shoppers and the way we narrowed it down, completed the sale AND received positive feedback for shipping the perfect pair of binoculars.

" I need a compact pair of binoculars suitable for concerts and sporting events under $100 "

In this particular case the first place I would start looking in is the compact section with a power range of no more than 7x magnification. Higher power makes it harder to keep up with the action on the field and you really don't want to miss all the action by being focused on just one player. The other recommendation was to go with a smaller sized zoom binocular which will offer you the capability of zooming in when you want to ( or if you are really sitting in the cheap seats :) however the price range was slightly higher then the recommended amount but by far a much more versatile binocular. In this case we sold the zoom binoculars and received a great response from the buyer.

Eye relief should also be considered and is the distance a binocular can be held away from the eye and still present the full field of view. Extended or long eye relief reduces eyestrain and is ideal for eyeglass wearers. Consider binoculars that have over 16mm of eye relief for eyeglass wearers.

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What Does " Exit Pupil " mean and how does that relate to me ?

Exit Pupil stands for the measurment of the circle of light that appears when you look through the binoculars holding them at a short distance away from your eyes. The exit pupil relates to how well a binocular will perform in dim light. If you hold binoculars away from your eyes and up to the light, you will see a bright circle in the center of the eyepiece. The exact size can be measured by dividing the objective lens by the magnification of the binoculars. A 10x50, for example, would have an exit pupil of 5 and a 7 x 42 binocular would have an exit pupil of 6 millimeters.

As a guide you should ensure that your binoculars have a similar size exit pupil to our own pupils. During low light conditions our eyes' pupils open to about 5 to 7mm wide to allow more light to pass to the pupil. So if you intend on using the binoculars during low light conditions or at night choose a pair with a similar value exit pupil. In bright conditions the pupils contract to about 2 or 3 millimetres and in such conditions the extra transmitted light isn't needed.

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The lens sizes are measured in millimeters (mm). Remember this is the second number in the equation. The human eye will adjust based on what you are viewing and the surrounding light conditions but the general rule of thumb is 5 times the magnification level. So if you are looking at a pair of binoculars that have 7x magnification, then you might want to consider a lens size of 35mm or a pair of binoculars listed as 7x35. A greater amount of light will enter through a larger lens size. This needs to be considered if you plan to use the binoculars for low light conditions or night viewing.

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What is a BAK-4 Prism?

Prisms are located inside binoculars that are like mirrors. It is a reflective coating on glass that bends and refracts light to bring the subjects you are looking at to your eyes. The BAK-4 prism is made of a high quality glass and produces sharp images and good edge to edge sharpness. . Generally, higher quality binoculars will use BAK-4 prisms in the construction process. Phase coated prisms take it one step further, the coating process enhances the resolution and contrast of images coming through the binocular and are generally applied only on more expensive binoculars.

Roof Prism System
In roof prism binoculars the prisms overlap closely, allowing the objective lenses to line up directly with the eyepiece. The result is a slim, streamlined shape in which the lenses and prisms that magnify and correct the image are in a straight line.

Porro Prism System
In porro prism binoculars the objective or front lens is offset from the eyepiece. Porro prism binoculars provide greater depth perception and generally offer a wider field of view.

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What does field-of-view mean?

Field-of-view is the size of an area that can be viewed using the binoculars. For example, if two people were standing 1000 yards away from you, one was to your left and one to your right and the distance between the two people was 350 feet, then your field-of-view would be 350ft at 1000 yards while looking through the binoculars. Generally, higher powered binoculars give you a smaller field-of-view and the opposite is true for lower powered binoculars. 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.

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What are lens coatings?

Ever look at a lake with the sun shining on it? Did you notice the glare coming off the water? Well, that's what happens to binoculars that don't have coated lenses. The lens coatings help to remove any glare and allow as much light as possible to enter the optics. The more expensive brands will have multiple coatings on ALL the lenses which will help to give the brightest and clearest images.

There are 4 levels of coating:

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

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