By: Robert Janis

Binoculars for Hunting

Bushnell legend roof prism binoculars in their new Mossy Oak break-up camo pattern.

If you are a fan of spectator sports such as football, baseball, basketball, soccer and more, or a bird watcher or hunter, you might find a need for binoculars to get the most out of what you do.

You may or may not be aware that there are several different types of specifications for binoculars. This information can prove imperative in finding the right binoculars for use in what you do. One might think that binoculars are binoculars. You see through them to watch the quarterback passing the ball, a batter at home plate hit the ball, a bird traverse from one limb of a tree to another, etc. Actually, binoculars need to do different things in order for you to get the most out of them for the hobby or sport you pursue.

So, for hunting there are certain things you need to know in order to select the proper binoculars for the task.

Binoculars’ Specs
There are three major specifications involved with binoculars-- power, field of view, and exit pupil.

Power is expressed as two numbers (8 x 42). The first number defines the magnification as a comparison to the naked eye. So in this example, binoculars that show an 8 as the first number is saying that it magnifies 8 times greater than the naked eye.

The second number, in this case 42, labels the diameter of the objective lens in millimeters. So, the number 42 means that the outer lens is 42 mm in diameter. A larger number indicates a larger lens. Larger lens are obviously more bulky, but they do allow more light gathering which makes the image you are viewing clearer, especially in low light conditions. This makes them ideal for a hunting scenario.

Field of View (FOV) is a term that explains how wide an area you can view through the binoculars. The measurement is in feet and the distance of view is 1000 yards. A higher number indicates a larger or wider area of view. One thing you need to keep in mind here is that as the magnification increases, the field of view becomes smaller.

What field of view you choose may be determined by what you are hunting and where. For example, if you are in a wide open area and you are seeking out mule deer, then experts in the know say that a narrower field of view is “not a big deal.” However, if you are in a dense forest area and you are searching for hidden black tail deer at a range of about 1,000 yards, then you should be using binoculars with a wider field of view.

Vortex Razor 8x42 Binocular

Exit Pupil helps to describe the power of the binoculars as well as the size of the objective lens. You can actually see the exit pupil. Just hold a pair of binoculars away from your face. You will see a small circle of bright light in the eyepiece. This is the exit pupil and can be measured in millimeters to determine the size of the beam of light that leaves the binoculars. The calculation is obtained by dividing the diameter of the objective lens by the power of the binoculars. As a hunter who pursues game at dawn or dusk, you will want to select binoculars with a larger exit pupil. That means more light is getting into the binoculars, and that’s what you want in order to see your target in the dimly lit period of dawn or dusk. Of course, you will be using the binoculars later on in the day as well as when there is clearly enough light. Those in the know say that a larger exit pupil will have little effect in the daylight. You may find that you may be able to move binoculars with a larger exit pupil in daylight and still maintain the image. That is a benefit for a hunter. Also keep in mind that if you select higher powered binoculars, those binoculars will also have to have a large size objective lens to maintain the same diameter of light leaving the binoculars.

Component Parts of Binoculars
An important component part of binoculars are the prisms. These are necessary because as light travels through binoculars it is inverted. In order to get the image in the correct configuration for your eyes and brain, prisms are used to correct the inversion. There are two main types of prisms--Roof Prisms and Porro Prisms.

A Roof Prism reflects the light 5 times, and the light comes out on the same line that it came in on. This design causes slimmer dimensions, a more compact body and usually lighter weight because the objective lens is in direct line with the eyepiece.

A Porro Prism reflects the light 4 times and comes out on a different line than when it enters the objective lens. That means a larger body to house the prism is necessary, and that means larger binoculars as a whole.
So now that you know there are two types of prisms that work in two distinctive ways, you need to also know that to help you select the binoculars with the proper prism you need to know the glass quality used in binoculars that feature Porro prisms. Porro prisms use two different types of glass--BK-7 and BAK-4.

BK-7 uses boro-silicate glass. BAK-4 uses barium crown glass. The BAK-4 is a finer, higher density glass that eliminates internal light scattering and produces sharper images than the BK-7 glass.

Optical coatings are another important element of binoculars. Coatings are used to help binoculars perform better than they naturally would. A very short lesson in optics tells us that the largest limitation of light transmission in binoculars is light that is reflected back. And in binoculars there could be as many as 10 different glass surfaces through which light has to pass. So, as much as 50 percent of ambient light can be lost. The coatings help to limit that.

So when you are comparing binoculars, you will see that there are many different types of coatings that are used. These include Coated, Fully Coated, Multi-Coated, Fully Multi-Coated, and Phase Shift Coating.

Coated Optics means that one or more glass surfaces on at least one lens have received an anti-reflective optical coating. Fully Coating means that all glass surfaces have been coated. Multi-coated means that one or more glass surfaces on at least one lens have received multiple coating. Fully Multi-Coated means that all glass surfaces have received multiple coating. Phase Shift Coating is used on the Roof Prism of many newer models of binoculars to correct for light loss on the horizontal image plane. This assures that there is no loss of contrast.
Finally, another factor to keep in mind when you are out looking for a pair of binoculars to buy is eye relief. The term describes the most comfortable distance that the binoculars can be held from the eyes, and still allows you to see the entire image.

Nikon Premier LX L binoculars

What You Do Affects What You Buy
It is said by those who know that the hunter needs binoculars that will perform best in the early morning and late evening. To achieve this you want binoculars that have bigger objective lenses that gather more light. Also, because of the nature of the beast, that means the binoculars you end up buying for hunting are bigger than for some other hobby or task.

Those in the know also suggest that you choose binoculars with 8x magnification. This provides all around magnification and a wider field of view. If you do a lot of sighting at long distances, then 10x binoculars may suffice; but these binoculars are large, thus heavier and, therefore, more difficult to hold steady.

Another feature that could be considered a must when selecting binoculars for hunting is that they should be waterproof. Another desirable feature for binoculars is that if possible they should be shockproof.

Here are some binoculars to consider:

Full Size Under $500

• Bushnell Legend Roof Prisms
• Eagle Optics Ranger SRT
• Leupold Cascades Porro Prism
• Vortex Diamondback
• Nikon Monarch
• Steiner Merlin
• Leupold Pinnacles
• Vortex Viper

Full Size $500 - $1,000

• Kahles
• Vortex Razor
• Bushnell Elite

Full Size $1,000 and Up

• Nikon Premier LX L
• Eagle Optics Ranger SRT
• Leica Ultravid
• Zeiss Victory FL
• Leupold Kamal
• Pentax DCF SP
• Pentax DCF HS
• Steiner Predator Porro Prism

Sources:
http://www.eagleoptics.com/index.asp?pid=3379
http://www.cabelas.com [ Cabela’s Binoculars Comparison Chart]