A few basic definitions to start. Binoculars are designated by their magnification and the objective lens diameter which is the light gathering lens; for example 7×35 means that the binoculars will magnify an object so that it appears seven times (7x) closer than it actually is. The number 35 represents the diameter of the objective lenses which are the light gathering lenses. Exit pupil is a specification that defines the size, in millimeters, of the light at the eyepiece and should match the diameter of the iris for an unvignetted view. Exit pupil is more important factor when using the binoculars during low light periods. Eye relief is a measurement in millimeters of how far back from the eyepiece the eye should be positioned to enjoy a full clear view. This specification is important for eyeglass wearers. Eyecups help to position the eyes correctly for the proper eye relief. Lower priced binoculars will simply have a rubber lip that cap be rolled down, whereas higher priced binoculars actually have adjustable eye cups that may have three or four preset positions for proper eye relief.  Field of View is a measurement of the width of the view at some standard distance down field, typically at a thousand yards. Depth of View is the total distance into the field that is in focus.

When selecting binoculars, the first thing to consider is how you will be using them. Is your primary use for hunting, while hiking a nature or scenic trail, stadium viewing, or perhaps you may be a birding enthusiast? Consider if the binoculars will be used during the twilight of dawn or dusk, certainly a critical time period for hunters and birders alike. Larger objective lenses will draw in more light during this period, however a larger objective also means it will be heavier. This could be an issue if they are carried around all day. A binocular harness will comfortably support the weight of full size binoculars and keep them handy as well.They support the binoculars at the chest when not in use and are reasonably priced. If a full day of lugging around heavier binoculars is not for you then by all means select a mid sized pair with an objective lens that is around 32 to 40 mm. Please keep in mind that the view may not be quite as bright as what the full size models can deliver. Do keep in mind though that higher quality glass in a smaller model can outperform lower quality glass in a larger model.

A binocular body style is based upon the type of prism that is utilized, either porro or roof. Porro prism binoculars are what we would define as the conventional style where the eyepieces are not in line with the objective lenses. Roof Prisms, however do have the eyepiece and objective lenses in line. Roof prism binoculars are more compact and rugged than Porros. Generally speaking, some Porros will produce a brighter image and greater depth of field than roof prisms of the same magnification, objective size and optical glass quality. Roof prisms manufactured by Zeiss use a phase coating technique on the prism glass to produce truly remarkable image quality.

Another consideration is focusing. Quick focusing is a must for the hunter or the birder. The complete focus range, from close focus to infinity, should be accomplished with a single stroke of the focus wheel. You need to be able to zero in as quickly as you can so that you maximize the time analyzing the object so you don’t waste precious seconds messing around with the focus wheel. If eliminating the hassle of focusing is important to you, then consider a pair of binoculars that have a greater depth of field. Once the diopter adjustment is set, everything in the view is in focus, whether it is 50 feet away or 500 feet. This style is preferred by the military. Fujinon manufactures high quality binoculars that are “focus free” and also have options for a reticle or built in compass. The close focusing specification of a binocular designates how close to the user the binoculars will focus. Any binocular can focus out at infinity, the trick is how close can the binoculars focus. The specifications are different for each model. Brunton and Zeiss have models with close focus specifications of three to six feet respectively. The close focus is a critical specification for birders and those who enjoy butterfly watching. If close focusing is important to you then select a binocular with a close focus specification of less than ten feet.

The next thing to verify are the lens coatings. Coated optics reduces the amount of light that gets reflected inside the binocular housing. As more light gets reflected rather than transmitted the result is a view with a reduced contrast of the scene or object. Look for lenses that are fully multi-coated. There are several coating designations that you should be aware of.
Coated optics only have a single layer on at least one lens surface.
Fully coated optics have a single layer on all air to glass surfaces.
Multi coated optics have multiple layers on at least one lens surface.
Fully multi coated optics- Multiple layers on all air to glass surfaces.

Will the binoculars be needed if it starts to rain? Don’t let a little rain stop you from achieving your goals for the day. Unfortunately just like any glass surface, the view may get distorted due to the moisture build up on the glass lenses. Once again this could be a time when seconds matter and stopping to wipe the lenses could result in a lost opportunity or perhaps even scratched lenses if you do not happen to have a soft lens cloth along. Zeiss binoculars have an additional proprietary coating called Lotutec, which actually causes water to bead up and roll of the lenses allowing continued use during a rain. There is truly a lot of value to that coating for the serious hunter or birder.

Now let’s talk more about magnification. When you look through a pair of binoculars you will see the field of view. As a larger magnification is selected, eye relief is reduced and a narrower field of view is available. In addition, as a larger magnification is selected it is more difficult to hold the binoculars steady enough by hand without getting movement. Additionally, in maritime use where the continuous bobbing and rolling produced by the water also creates motion, a smaller magnification and larger objective lens size will allow for more forgiveness for the movement. So select magnification carefully, as 7x or 8x powers will work fine for most applications. If higher magnifications are needed for land applications, then consider purchasing a tripod or other support. Image stabilized binoculars are ideal for maritime use.

Finally, color and clarity of the view is the most important feature that differentiates premium binoculars from less expensive binoculars. These are quality features that certainly birding enthusiasts demand and hunters as well. To be able to pick out detail and colors from a camouflaged background can mean the difference between spotting the object of interest and missing it completely.

If you have enjoyed this article or desire more information and assistance with binocular selection please visit http://www.rcsoptics.com

Copyright 2009 RCS Optics, all rights reserved. This document may be copied and distributed freely on the web so long as the content, links, author and copyright information remains intact and unchanged in any way whatsoever.

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