Binoculars: What You Need To Know.
With turkey season coming up soon, it’s a good time to talk about how to chose a pair of binoculars, one that works for you and the way you hunt. If you are in the market for binoculars for hunting you should be familiar with some common features and specifications so you will get the best set of binoculars for what you plan on spending.
In this article I’ll cover some features and specifications you should understand before you purchase a set of binoculars. As with most products, there is always a give and take. One feature may sacrifice another so you really need to define what’s important to you and how you plan to use them.
The first thing you’ll probably notice are the two numbers separated by an ‘x’: 8×32, 10×42, 12×50, etc. A larger number means a better view, right? Not necessarily so let’s break down the features into sections in a 10×42 pair of binoculars.
The first number, ‘10’ is the power, or how many times the image is magnified. In a 10×42 the object you are looking at will appear 10 times larger than it would with just your eyes. It would seem you would want binoculars with the most magnification, but it really depends on what you are looking at. If you are a bird watcher, a higher magnification may offer more details, but a magnification power higher than 10x will be difficult to hold steady by hand. For typical hunting situations 10x is about as high as can go and still manage a steady view.
The ‘42’ is the diameter (distance across) of the objective lens (in millimeters); the objective lens is the lens farthest away from your eye when you look through the binoculars. The larger the diameter of the objective lens the brighter and clearer your image will be. A larger diameter is nice because it lets in more light and gives you a wider viewing area. However, larger lenses can be heavier and require a larger binocular housing and the extra weigh can limit portability.
Do you have room in your day pack for the size of binoculars you are getting? If you use a harness you also won’t want something too big and bulky hanging from your shoulders.
A front lens diameter of 25-30mm would be perfect for hunting binoculars, unless you plan on using them a lot in low light conditions, in which case you may want a larger front lens diameter. This is a perfect example of the give and take situation with the different features.
So, even if you have the money, you probably don’t want to go out and buy the longest zoom and the biggest diameter lens you can afford. In most hunting situations a mid-range magnification of 8 to 10 is ideal. It’s hard enough to steady binoculars when you are holding them to your eyes, especially if you need to watch moving animals. If you had a 12x magnification binoculars the jittery image while trying to focus on your game can be frustrating.
Field of View
Field of view is a measure of the area that can bee seen at 1,000 yards. It decreases as magnification increases, which is another reason why higher magnification doesn’t always make for the best viewing. Remember to keep field of view in mind while taking other features into consideration.
There are two types of binocular shapes. Those with a slim, inline style with a more compact shape are called Roof Prism binoculars and they have lenses inside the housing that are lined up, or ‘in line’. Most hunters prefer the more compact, less bulky design of the roof prism binoculars. With the inline design you lose just a little bit of light, which would enhance image clarity, but the difference is barely noticeable if you are comparing binoculars in the same price range.
Porro Prism binoculars are easy to recognize as they are the clunky looking, traditional style binoculars with two connected, separate lens barrels. The lenses inside the porro prism binoculars are offset, allowing more light to enter and giving the image a brighter, clearer image, particularly in lower light. Porro prism design requires a little more care and can be a little bit heavier.
Exit pupil is another indicator of how bright your view will be. The larger the exit pupil, the more light will enter the housing. To get the size of the exit pupil in millimeters, divide the objective lens diameter (In our example, 42) by the magnification (10). Simply put, the larger the exit pupil the brighter your image will be.
An exit pupil size of 5mm or larger is what the average hunter is looking for.
If you have a chance to hold the binoculars and try them out, hold them up to look through them while paying attention to how they feel in your hands. In your opinion, do they feel balanced? Adjust the hinge between the two housing barrels and make sure it adjusts easily to fit your face. How do they feel in your hands?
If you wear glasses check the retractable or rubber eye cups for adjustability and fit. Check the focus dial to feel how comfortable and easy to adjust it is. Fine-tune the diopter adjustments to make sure you can easily get a clear image. The diopter adjustment is usually a little knob to adjust the image according to slight differences that your right and left eye may have.
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