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How to choose binoculars for birdwatching

Binoculars of about 8×40 to 8×42 suit most birding. Good, affordable binoculars used every week beat expensive ones left in the cupboard. Here is what the numbers mean, how to test a pair, and how to set them up.

What the numbers mean

Take 8×42 as an example.

• 8 is the magnification. The bird looks eight times closer.
• 42 is the width of each front lens in millimetres. A bigger lens lets in more light, so the image is brighter at dawn, at dusk and in forest, but the binoculars are heavier.

8× or 10×?

• 8× gives a wider view, which makes birds easier to find, and a steadier image. It is best for gardens, bush, forest and beginners.
• 10× gives a bigger image but a narrower view, and it magnifies your hand-shake too. It suits open country, wetlands and distant birds.

Most beginners, and most birders, do best with 8×. Compact binoculars such as 8×25 are light but dimmer.

What to look for, in order

1. Comfort, and a sharp, bright image to your own eyes.
2. Magnification of about 8×, with a front lens of 32 to 42 mm.
3. A wide field of view.
4. Close focus of about 2 to 3 metres or less, for garden birds.
5. Waterproof and fog-proof.
6. Long eye relief if you wear spectacles.

Very cheap binoculars are often blurred, dim or out of line, which gives headaches. A mid-priced pair from a reputable shop usually lasts many years, and a second-hand pair can be excellent value if it passes the tests below.

Test before you buy

• Look at fine detail far away. Is it sharp in the middle and fairly sharp at the edges?
• Look into shade under a tree. Is the image bright enough?
• Look at a pole against the sky. Are there strong coloured fringes?
• Use them for a minute. Do your eyes feel strained?
• How close can you focus?
• With your spectacles on, can you see the whole round image?

Set them up once

1. Eyecups: up if you do not wear spectacles, down if you do.
2. Width: bend the two barrels until you see one round image.
3. Dioptre: close your right eye and focus with the centre wheel until the image is sharp for your left eye. Then close your left eye and turn the dioptre ring, usually on the right eyepiece, until it is sharp for your right eye.
4. Strap: shorten it so that the binoculars hang on your chest.

Finding the bird

Beginners point the binoculars at the sky and search. Instead, keep your eyes on the bird and bring the binoculars up to your eyes without moving your head. Then focus. Hold them with both hands, elbows tucked in against your chest.

Never look at the sun through binoculars.

Care

• Keep the lens caps on in dust.
• Blow or brush grit off the lenses before you wipe them with a lens cloth. Never use a shirt or a tissue.
• Do not leave them in a hot car.
• Note the serial number, because binoculars are easily stolen.

The rest of the kit

A field guide to the birds of southern Africa, a small notebook and a pencil matter as much as binoculars. Wear dull colours, a hat and closed shoes. If money is tight, buy the guide first and borrow binoculars while you save.

This guide is based on Chapter 2 of Birdwatching in Southern Africa, which also covers field guides, apps and keeping a notebook.