If asked, most people would turn down help when selecting a pair of binoculars. Most likely, their predominant selection criteria are based upon either magnification or the price. After all that is all there is to it, right?
Well... No. You will need to balance your personal expectations of the quality of the view, the functionality required and your budget. These factors will dictate the correct pair for you. Also there is give and take with binocular specifications, so you need to know what you are giving up by selecting other features or specifications so that you can make an informed purchase that you will be satisfied with for years to come.
Lets Define Your Expectations.
Binoculars are typically used while birding or hunting, during stadium events or races, for astronomy, or even while day hiking scenic or nature trails. When you look through a pair of binoculars you're observing the field of view. (We will get to the definition in a minute). In each of these activities, the user wants to get a closer look at the subjects in the field of view. The quality of that view can vary significantly from different manufacturers even though the comparisons are made between the same magnification and objective size. The quality of the view needs to meet or exceed your expectations.
You see, a birder desires to see the coloring and detail of the subject, in this case perhaps the feathers of a rare bird. This could also be viewing any scene where razor sharp images are desired. Day long hikes at a birding festival are not uncommon. Often times birds may actually approach the viewer, so quality glass, light weight and a close focus specification are desired specifications that should be considered. The close focusing specification of a binocular designates how close to the user the binoculars will focus. Every binocular will focus out at infinity but the close focus specification is different for each model. 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 pair that has a specification of ten feet or less.
When looking at a high contrasting image in the field of view you may not realize it at first but upon close inspection you may see thin bands of color outlining the edge of dark objects, rendering them fuzzy and dull due to unfocused light. This is called color fringing. In some binoculars this effect can be seen throughout the entire field of view and can even grow dramatically as you approach the edge of the field of view. You need to ask yourself if you are willing to live with a less than a bright, sharp and vivid field of view. Quality glass is essential.
Wide Angle & Focus-ability
A hunter will most likely not need to be concerned with the close focus specification as his subject is typically much farther away. The same is true of astronomy, stadium events or races. The user is not concerned about loose threads on a jersey, somebody's tattoo, or the fabric texture of a jockeys cap. In these cases the typical expectation is to see the action. The more the better. Here a wide angle view is much more desired because the user not only wants to see the receiver, but the defenders and other players in the area as well. Compare field of view specifications and select a larger value.
If the action covers a fairly large area, a feature to consider would be nonfocusing style of binoculars; also called focus-free or perma-focus, this type of binocular does not have a focus knob as the lenses are designed with a very deep field of view. They are fitted with individual eyepiece (diopter) adjustments that once set, leaves everything in focus regardless of the distance away from the user. So if you enjoy getting into the action without having to consciously keep readjusting the focus knob as the action moves around then consider this type of binocular. It will let you concentrate on and enjoy the action! Since each eye needs to be adjusted these are not the pair to be sharing with friends at an event as everyone will need to establish settings for their own eyes. Perma focus binoculars usually have a poor close focusing capability. Do consider the ease of focusing if focus free style is not desired. Quick focusing is simply a must regardless if used by the hunter or the birder. Look for a pair of binoculars that can focus from close up out to infinity with a single stroke of the finger. You need to be able to zero in as quickly as you can so that you maximize the time analyzing the object. You don't want to waste precious seconds messing around with the focus knob.
Twilight Use
Consider if the binoculars will be used during the twilight of dawn or dusk, certainly a critical time period for hunters and birders alike. Binoculars with a larger objective lens (42-56mm) will help draw in more light during this time, however, at around 2 to 3 pounds; they will also be heavier if they will be carried around all day long. A binocular harness can help support the weight of full size binoculars without the muscle fatigue associated with a neck strap. Harnesses support the binoculars at the chest when not in use, even when bent over to pick something up and are reasonably priced. If a full day of lugging around heavier binoculars is not for you then by all means select a midsized 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. However higher quality glass and lens coatings can drastically affect light transmission, and in those cases a midsize pair with quality glass and multicoatings can outperform a larger binocular that uses lower grade glass without multi-coatings.
A word about compacts. Yes they are typically less expensive, however when it comes to compacts they give up all the quality features that standard size binoculars have. What you are buying is the feature of compactness. What you are losing is a clear, bright view. Compacts should be considered as a secondary pair that you can stow in the glove compartment or a fannypack- but not for your primary pair.
Lens Coatings
The next thing to consider are the lens coatings. Due to the laws of physics, some of the light that reaches the lens surface gets reflected back. Coated optics help to reduce the amount of light that get reflected. As more light gets reflected rather than transmitted the result is a view with a reduced contrast of the scene or object in the field of view. Fully multi coated lenses are most desirable. It is important to note that a lot of research has gone into different lens coatings and not all coatings are created equal. As a general guideline...
Coated optics- A single layer on at least one lens surface.
Fully coated optics- 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- have multiple layers on all air to glass surfaces.
Rain or Shine
What is the likelihood that you will need to depend upon your binoculars during a rainstorm? Most all of us, when in the field, want to make the most of the opportunity and generally don't let the rain spoil our fun. 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 have a soft lens cloth along. Several manufacturers have an additional proprietary coating which actually causes water to bead up and roll of the lenses allowing continued use during a rain. This is not a replacement or alternate coating to fully multicoated lenses. These coatings truly provides a lot of value for the serious hunter or birder.
Specs Are Important Too
Binoculars are designated by their magnification and the objective lens diameter; for example 7x35 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 in millimeters, which are the light gathering lenses.
Exit pupil is a optical 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. It is calculated by taking the objective lens size and dividing it by the magnification. The average pupil dilates from about 2mm in bright sunlight to 7mm in low light. This range varies with age as well. ( Most adults average around 5 mm) Exit pupil specification is more important factor when using the binoculars during low light periods. Manufacturers design mid and full size binoculars with Exit Pupil in mind. The only exception to this is compact binoculars which have a very small exit pupil specification- typically in the 2.0 to 3.0 mm range.
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. Short eye relief does not allow an eyeglass wearer to see the full field of view because the user cannot get the binoculars close enough to their eyes. Eyecups are included to help position the eyes correctly. The system employed could be as simple as a rubber lip that rolls down or it could have adjustable cups that have twist up presets, which is much more desirable.
Field of View is a measurement of the width of the view at some standard distance downfield, typically at a thousand yards- for example 300 feet at 1000 yards. Depth of View is the total distance into the field that is in focus.
A binocular's 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, on the other hand, do have the eyepiece and objective lenses in line. Roof prism binoculars are more compact and rugged than Porros but more costly to manufacture.
Optional Features for Hunters
Some binoculars are available with rangefinders or mil-dot reticles and even compasses that can be viewed in the binocular while using them. Combining features allows hunters to carry less tools on the hunt while providing tactical information that will help the user to be more successful.
More Give and Take
Now let's talk more about magnification. As magnification is increased, the field of view will get narrower and eye relief is also reduced. In addition, as a larger magnification is selected it is more difficult to hold the binoculars steady enough by hand without getting movement in the field of view. These compromises are easily noted while using a zoom style binoculars that allows a variable magnification range, for example 10x to 30x. 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 support such as a tripod. Image stabilized binoculars are ideal for maritime use.
A Little Bit about Budget
Being an informed consumer is very important. Making the proper selection of Binocular specifications is critical to meeting your needs. As you noticed as you read through the article, there is give and take with different specifications. Only you will know what binocular specifications will satisfy your needs. If this is your first binocular purchase then it is recommended that you: 1) do not buy compact binoculars, 2) keep the purchase value between $100 and $250 and 3) do not buy binoculars made in China.
Final Thoughts
Finally, color and clarity of the view are the most important features that differentiates premium binoculars from less expensive binoculars. Serious hunters and birding enthusiasts alike demand these quality features. Having a view that allows you to pick out detail and colors from a camouflaged background can mean the difference between spotting the object of interest and missing it completely. High quality binoculars will produce vivid, detail colors even in the deepest twilight.
