Take on Nature: A quick guide to choosing the best binoculars for birdwatching

It’s worth remembering that binoculars are a very useful but not essential tool in helping us observe and enjoy the birds around us
Stephen Colton

I AM sometimes asked for advice on buying binoculars or ‘bins ‘as they are often referred to in the birdwatching world.

Binoculars are useful to the birdwatcher whether as a beginner or a more experienced user. They come in various shapes and sizes, ranging in price from around £100 to over £1,000. Understandably, better quality comes with the more expensive brands which are superior in terms of image sharpness, colour definition, design and durability but these are really only for the professionals. There are many good quality binoculars out there in the more affordable categories.

After financial considerations, there are other important things to look out for which will determine the quality of your product. All binoculars are defined by standard specification figures, which appear on the front of the set. These figures will appear as; 8 x 32, 8 x 42, 10 x 42 or 10 x 50. The first of these numbers indicates the magnification or how many times larger the object you are observing will appear. The second figure is a measure of the diameter in millimetres of the objective lenses, at the bottom of the binocular.

The combination of these two figures is very significant as it affects the overall performance of your binoculars in terms of power, brightness of image and field of view. Do not automatically opt for the highest magnification. Anything above a 10 magnification is difficult to hold steady by hand and will probably produce a dull image, so avoid persuasive offers of brands boasting a 20 magnification at some apparently brilliant price. These will be of poor quality.

Ideally, what you want is a combination of good magnification and objective lens diameter. The diameter figure is important because the wider it is, the better the light-gathering potential of the binocular and overall brightness of what you see. So good magnification with good light intake is the ideal combination.

However, as objective lens size increases, the physical size and weight of the binocular also increases. A good rule of thumb to help get the right compromise involves doing a quick calculation with the two figures – divide the diameter by the magnification number; For example, 32 ÷ 8 gives a figure of four, a reasonably good light intake. The higher this number, the brighter your image will be.

Another choice might be 42 ÷ 8 giving a light index of approximately five. This binocular will give a brighter image but will be a little heavier than the 8 x 32 model which has the same magnification with marginally less light. A combination of a 10 x 50 binocular gives you powerful magnification and good light but it will be heavier again, so many birdwatchers choose a combination of 8 or 10 magnification with an objective lens size of 32 or 42, giving a good blend of power, light and weight.

I use an 8 x 32 pair which are more than adequate for most bird watching, lightweight with good magnification and a bright image. For sea watching or observing at tidal mudflats and lakes, I use a 10x set which give added magnification for identifying more distant species.

Take time when purchasing and test binoculars outside stores or at public trade stands. After all that technical detail, it's worth remembering that binoculars are a very useful but not essential tool in helping us observe and enjoy the birds around us. We don't need them in our garden, by our workplace or on regular walks. The best tools of all are our eyes and ears.

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