There are a daunting number of sizes and styles of binocular on the market, though, so how do you know what’s best for you? Here’s a simple guide to buying binoculars that will give you tips on what to look for and how to choose the perfect pair.
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Buying a good pair of binoculars is a worthwhile investment as it will make a big difference to your wildlife watching experience. If you have spent your hard-earned money on a fabulous wildlife holiday, you’ll want to be sure you get great views of the animals. Even at home, watching the birds on your feeders is so much better if you can observe them close-up.
What To Look For When Buying Binoculars For Wildlife Watching
When you set out to buy a pair of binoculars you will see a series of numbers, usually on the dial between the two eyepiece tubes. The first figure refers to the magnification that the binoculars offer. The second figure refers to the diameter of what are called the ‘objective lenses’. These are the eyepiece lenses that are furthest away from you as you hold the binoculars to your eyes. Or closer to the ‘object’ you are looking at, hence the name.
Photo Credit: Virginia State Parks
So, for instance, if the figures are 8×32 that means that pair of binoculars has an eight times magnification and the front lenses are each 32mm across.
Wildlife watching is best done with binoculars that are 8×32 or 8×42. This is eight times magnification and a 32mm or 42mm diameter front lens. Why is this? You might think greater magnification will give you even better views. So why not get 10 times magnification or 12 times?
The reason for sticking with 8 times is: the greater the magnification, the smaller the field of view. The smaller the field of view, the harder it is to locate the animal you’ve just spotted. This is especially true if you have to lift the binoculars to your eyes quickly. For instance, if you’re trying to see a small bird you’ve heard flitting about in a tree. It would equally apply for any wildlife watching. If you were trying to see the action in the middle of a herd of wildebeest, for example.
Why Does The Diameter Of The Front Lens Matter In Buying Binoculars?
The bigger the objective lenses, the more light is let into the body of the binoculars and so the brighter the image will appear to your eyes. Small pocket binoculars will give you just as much magnification. But their smaller front lenses will not allow such a bright, clear view of your wildlife subjects as bigger ones would.
So, if you aim to buy binoculars of the recommended sizes, what’s the difference between buying 32mm and 42mm? Surely 42mm will let in more light and therefore be better?
That is certainly true, but it’s also to do with weight. Binoculars with 42mm lenses are slightly bigger and heavier than those with 32mm lenses. If you are wearing them around your neck all day while you’re out wildlife watching that increased weight can make a difference.
The Two Types Of Binocular Shapes
Binoculars come in two basic styles, known as Porro Prisms and Roof Prisms, and they are easy to tell apart. There are pluses and minuses to buying binoculars of each type so which you choose will be down to individual taste and how they feel in your hand.
The ‘prism’ part of the name refers to the wedges of glass that are found inside the tube of each eyepiece. For the purposes of this buying guide, it’s not necessary to go into too much detail about the workings of binoculars. Suffice to say, the image coming into the eyepieces is distorted by the convex curve of the lenses and the prisms rectify the distortion.
Photo Credit: Shutterstock – Porro Prism binoculars
These are binoculars that contain two prisms set at an angle to each other. The eyepiece tubes are constructed with a ‘dog leg’ in the middle to accommodate the two prisms. These are the types of binoculars that used to be standard – their appearance will be familiar from vintage models. Their advantage is that at the budget end of the market these binoculars work very well. However, they are not so compact nor considered to be as durable as the style known as Roof Prisms.
These are binoculars in which the prisms are aligned, one in front of the other. In appearance, therefore, the eyepiece tubes are straight from front to back. This style of binocular has become the more popular option over the past 20 years or so. They are more complicated and precise to make but they are also more robust and some consider they feel better in the hand.
However, in the budget buying range of binoculars, Porro Prisms tend to be better than Roof Prisms. But in the mid-price range, and above, Roof Prisms tend to win out over Porros.
Photo Credit: Shutterstock – Roof Prism binoculars
As a final note on prisms, you may come across references in the user literature to different types of prism being incorporated in a particular pair of binoculars. BAK4 prisms are more finely ground and therefore slightly better quality than BK7 prisms. But these days most mid-range onwards binoculars will be good, whichever of these is used.
- Objective lens – the front end of the binoculars
- Ocular lens – eye end of the binoculars
- Exit pupil – calculated as the diameter of the objective lens divided by the magnification, which gives the diameter of the beam of light that comes down each eyepiece to the retina of your eye. This doesn’t really matter in daylight but for dusk and dawn wildlife watching you need to be looking for binoculars with a big exit pupil.
- Eye relief – the distance between the ocular lens and the exit pupil. In other words, the distance from where the light enters the binoculars to where it hits the middle of your eye. If the eye relief isn’t set correctly you’ll see black circles around the image.
- Diopter – the focusing wheel that is part of the ocular lens on the right eyepiece. You set this on first use but then it is left alone. This corrects any differences in vision between your right and left eyes. All the subsequent focusing is done with the centre focusing wheel between the two eyepieces. The diopter should therefore not turn too easily as that will make it prone to being accidentally moved out of its setting.
- Centre focusing wheel – unlike the diopter, this should be easy to move and not too sensitive.
What Else Makes The Difference To The Cost Of Buying Binoculars For Wildlife Watching?
The pricing when you’re buying binoculars is dictated by the quality of the lenses and the prisms inside the eyepieces. The higher the quality of the glass, the more light passes through it. Cheaper prisms cause shading around the edges of the image and it appears less clear. So cheaper binoculars are not so good on overcast days, at dawn or dusk. The top-quality lenses and prisms that come in high-end binoculars allow you to use them in very low light. Sometimes it is even possible to see things reasonably clearly when the light levels are too low for your own eyes.
There are also some desirable qualities and additions to a pair of binoculars that can justify paying slightly more than a basic price.
Gas-filled Eye Tubes
This means that the air inside the eye tubes has been replaced with nitrogen. It makes the air- and watertight and stops the binoculars from fogging up when the temperature changes suddenly. You usually get this with higher-end binoculars.
Photo Credit: Shutterstock – Fixed Eyecups
Binoculars will either have fixed or twist-up eyecups. Both types of eyecup are designed to ensure your eyes are the correct distance from the binocular lens to give you a clear, undistorted view – this is what is called the correct eye relief (see Binocular Terms). They also help shield your eyes from strong sunlight. With fixed ones, the eyecup forms a lip around the lens to give the eye relief, but they do not move. With twist-up eyecups they start out flush with the surface of the lens but you can screw them up in stages to suit what is comfortable for your eyesight and gives you the clearest view. These are recommended because they give you the most flexibility, especially if you want to use the binoculars with spectacles. With some fixed eyecups you can fold back the rubber if you are wearing glasses, but this doesn’t give you the same degree of control.
Coatings On The Lenses
These reduce reflected light, which increases the amount of light that reaches your eye and gives you a clearer view of your subject.
If your wildlife watching leads you to study insects or you’re a keen botanist, check how close you can get to the subject and still be able to focus. The higher-end binoculars tend to give you the ability to focus very close to the animal or plant and really see the detail. Less expensive types will only allow you to focus up to about 150cm away from the subject.
If at all possible ‘try before you buy’ your binoculars. If you can, find a photographic shop or optics retailer where you can hold the binoculars, look through the lenses, play with the focusing and compare makes and models. Not every make or size will feel comfortable in your hands or work with your eyes. You can pay a lot of money buying high-end binoculars but that won’t guarantee that you get on with them.
Photo Credit: Steve Hillebrand – Trying out binoculars
Also, looking at a range of objects at different distances using a number of different binoculars should highlight any shortcomings in the quality of the lenses. For instance, there may be evidence of a slight curvature of view where straight lines are not perfectly straight. Or what you are looking at maybe a little soft around the edges or have a ‘halo’ of colour around it. These faults only matter in the degree to which they affect your view of your subjects. If you’re happy with all other aspects of the binoculars you are considering, then you may be prepared to put up with a small amount of softness or curving.
So, to sum up, although the view through the eyepieces is paramount, of course, ease of use and comfort are also very important. After all, you may well be buying a pair of binoculars that will last you a lifetime of wildlife watching.
SETTING UP YOUR BINOCULARS
Photo Credit: Ashley Spratt USFWS – Crowd watching Monarch Butterflies
Once you have chosen the ideal pair of binoculars for your wildlife watching needs and budget, you have to set them up to get the best view.
- First, adjust the distance between the two eyepieces by opening or closing them where they hinge until you are happy you have a single clear view through them. There should be no dark circles interfering with the image, even if it is not yet in focus.
- Cover the right objective (front) lens with the lens cover or your cupped hand and choose a point in the mid-to long-distance to focus on.
- Use the centre dial between the eyepiece tubes to adjust the focus in the left eyepiece until your chosen object is seen clearly.
- Uncover the right objective lens and cover the left one.
- Look towards the same object as before but this time use the ring around the right eyepiece, the diopter, to bring the object in the right eyepiece into clear focus.
- Uncover both lenses and, from then on, only use the centre dial between the two eyepiece tubes to do all the focusing.
You may have to repeat these steps if the light conditions change and it gets much brighter or much dimmer. You may also have to adjust the binoculars the next time you take them out, as the diopter sometimes gets nudged out of place in storage.