How To Choose Binoculars For Animal Watching (Best UK Guide)

If you enjoy watching wildlife, whether at the local park, safari park, zoo, in the countryside or even in your own garden, a decent pair of binoculars will help you to see the animals up close without disturbing them. There are so many types of binoculars on the market nowadays that choosing the right pair for you can seem daunting. But don’t despair because we have all the information you need to get the perfect pair of binoculars for animal watching.

What Do You Need To Consider When Buying Binoculars?

There are a few features that you’ll need to consider before you purchase your binoculars so let’s start at the beginning and work our way through them.

What Size Binoculars Do You Need For Animal Watching?

Binoculars are available in three sizes which are determined by the size of the objective lens diameter. Firstly, the objective lens is the larger of the two sets of lenses, the ones closest to the object you’re looking at. The three sizes are;

1. Compact
   These are the smallest binoculars available and they have an objective lens diameter of less than 30mm.
2. Mid Size
   These have an objective lens diameter of between 30 to 40mm.
3. Full Size
   Any binoculars with an objective lens diameter of more than 40mm is considered to be full size.

Magnification & Objective Lens Diameter

These are probably the two most important factors of any binoculars so it’s important to get these right. The magnification is how much larger any object will appear through the binocular lenses. The objective lens is the one at the front of the binoculars and its size is important because it’s the only way light can enter the binoculars and so the only way any image is illuminated.

To find out the magnification and the objective lens size just look on the body of the binoculars. You’ll see a series of numbers separated by the letter X, something like 8×25, 10×42 or 7×35. The first number(s) indicates the level of magnification so 8x means the objects viewed through that particular pair of binoculars will appear 8 times larger than with the naked eye (the X indicates times). 

The numbers after the X are the diameter of the objective lens in millimeters so 8×25 indicates 8 times magnification with an objective lens of 25mm. Any magnification greater than 10x will result in a blurred image due to our natural arm shake caused when holding any object for long periods of time.

What Else Do You Need To Know?

After the magnification and the objective lens diameter there are a few more features that are quite important to know about the binoculars specifically for animal watching. Let’s start with;

The Field Of View

The Field of View (FoV) is the area that can be seen through the lens of the binoculars at 1,000 metres distance. In the specs it’ll look something like 105m@1,000m or 140m per 1,000m, so this tells us that at a distance of 1,000 metres we’ll be able to see a width of 105 m or 140m respectively. Incidentally 105 to 140m per 1,000m is the expected FoV of a decent pair of binoculars.

What it tells us in practical terms is that at 1,000m we will be able to see 105m from left to right without moving our head. So if for example we see a bird sitting on a fence between two posts that are 50m apart, we’ll be capable of seeing the whole of that image through the lens of the binoculars without moving.

Exit Pupil

The exit pupil is the beam of light that shines through the objective lens and reaches our pupils to light up the image we can see through the lenses. The human pupil dilates to around 6 to 7mm in low light conditions and shrinks to around 2.5 to 3.5mm in bright daylight. So if you’re planning on animal watching during the hours of daylight any binoculars with an exit pupil of between 2.5 and 4mm will be more than sufficient for your needs.

If the exit pupil isn’t quoted in the specs, it’s an easy one to calculate. Just divide the objective lens diameter by the magnification, the result is the exit pupil in millimeters. For example a pair of binoculars with a magnification of 10x and an objective lens diameter of 50 (10×50) will have an exit pupil of 5mm because 50፥10=5.

Eye Relief

The eye relief is the distance between the eyepiece (ocular lens) and your eye at the point of being able to see the whole image clearly through the binocular lenses. For most people an average eye relief of between 11 to 16mm is fine. However, if you wear glasses, you might need long eye relief which is between 16 to 24mm. Check the binocular specs for specific eye relief values.

Is It Necessary To Have Waterproof Binoculars For Animal Watching?

In some ways this depends on where you plan on watching animals, if for example you plan to sit indoors looking out through the window to watch the animals in your garden, then waterproofing isn’t necessary. For any outdoor activity however, we would recommend waterproof binoculars. There are some unscrupulous companies that imply waterproofing when their products aren’t actually waterproof. Terms like “water resistant” and “weather proof” often mean very little, to clear up any uncertainty the industry came up with an ingress code.

Unfortunately this code is somewhat confusing, but a pair of binoculars with an IPX6 will not allow any rainwater to enter the lenses from any angle. This will be more than sufficient for most activities except boating or watersports.

Fog Proof

The problem with any optical equipment is the susceptibility to steaming up in fluctuating temperatures. Leaving a warm car and standing in a cold field to watch some rare red squirrels could lead to the binoculars fogging up. To prevent this, the manufacturers remove all the air from the lens tubes and replace it with an inert gas like nitrogen. As this gas contains no moisture it cannot react to extreme temperature fluctuations.

Better Light Transmission Leads To Clearer Images

As we said earlier, the only light that can give the image we see through binoculars any brightness enters through the objective lens. For a clearer image you need better light transmission, to achieve this, the prisms and lenses are made from better quality glass. The top quality binoculars use BAK4 glass for the prisms, this is top quality precision optical glass with a low level of imperfections.

This allows the light to travel easier creating clearer images. The most common glass used in the production of binocular prisms is BK7 glass. This is still precision optical glass but has slightly more imperfections and thus creating a slightly less than perfect image. The lenses of the best binoculars are made from Extra-low Dispersion glass. ED glass gives an improved brighter image with better contrast and full colour retention with no fringing or haloing.

Lens Coatings

To improve the light transmission even more, a special coating is applied to the lenses that also reduces glare too. There are a number of different coatings but as far as we can tell, the best are FMC (fully multi-coated) which means every lens inside and out are coated in multiple layers to improve brightness, contrast, light transmission and reduce glare.

Clearer Images Means More Detailed Animals

To be able to see the animals you’re watching in closer detail you need clearer images, which in turn, are assisted by better light transmission. Imagine watching wild otters in their natural environment, beavers building their wooden home in a local river or even just being able to distinguish between male and female robins.

All of this is possible with a good pair of binoculars, and just because they’re good enough to have all of the features above and have better light transmission doesn’t mean spending a fortune. There are 8×42 binoculars with FMC lenses, BAK4 roof prisms, rubber coated body, waterproof and fog proof, nitrogen purged, 18mm eye relief, 129.5m @1,000m FoV, and an exit pupil of 5.3mm, all for less than £150.00

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