Choosing scopes and binoculars: A beginner’s guide

Buying optics for the first time can be bewildering, but our expert David Chandler will help you focus on finding what's right for you.

Couple birdwatching in a forest. © Amy Eckert/Getty

Binoculars and telescopes offer fantastically close views of wildlife and will enhance days out for years to come. But with so many products on the market it can be hard to know where to start. You need to consider carefully what you need from your optic, and how easy it will be to use.

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Our expert guide provides an introduction to choosing binoculars and telescopes (often shortened to bins and scopes by birders), including an explanation of the different terminology and how to test a product.


How much do binoculars and scopes cost?

Prices range from less than £100 to more than £2,000 for binoculars, and less than £150 to nearly £3,000 for scopes. But you can get good optics at much lower prices than the top-range products, and can always buy second-hand.

As well as budget, consider what you will be using your optic for. Is it mainly for watching birds and mammals? Do you want to look at insects in detail? How much low-light watching will you do?


What do all of the numbers mean?

An 8×42 pair of binoculars magnifies 8x – so the subject is eight times closer – and has a 42mm objective (light-gathering front lens). A 25–60x 85 scope magnifies from 25x to 60x, and has an 85mm objective. Most wildlife watchers use 8x, 8.5x or 10x binoculars. Bigger magnification isn’t necessarily better, though – the field of view tends to be narrower, and the optic is harder to hold steady.

Scopes can have fixed magnification or zoom eyepieces. A zoom gives you options, but decent ones are expensive. For a fixed magnification, something around 30x is a good choice. If there’s a wide-angle option, go for that.

All things being equal, the bigger the objective lens, the brighter the view. In terms of the objective size, 32mm or 42mm binoculars are popular choices. If you want a smaller, lighter pair, and don’t need low-light performance, compact binoculars with 20–25mm objectives are also worth a look.


Is weight an issue with scopes?

If you want to travel light, you could try a 50mm scope, but you will sacrifice low-light performance. If you want to digiscope (take photos through your scope) then choose a bigger objective, because more light will get to the camera.


What’s best for low light?

The size of the objective determines how much light enters a pair of binoculars or a scope. How much comes out the other end depends on the design, glass and coatings. A bigger exit pupil (see box) gets more light to the eye.

But our pupils become less able to dilate as we age, so you might not be able to use the extra light. An 8×42 gets more light through than a comparable 8×32, but you may not see it.


What about scope design?

Scopes can be straight, with the eyepiece in line with the objective, or angled, with the eyepiece pointing upwards. Angled scopes take some getting used to. You look down into the eyepiece – this is comfortable and enables you to set your tripod lower, increasing stability. Angled scopes also make it easier to share the scope with people of different heights. A decent tripod is essential too.


Tips for testing out binoculars and telescopes

  1. It’s best to try out several different binoculars before you buy, and in poor light conditions. Choose a seller with a good returns policy.
  2. Make sure the image is sharp, bright and easy to focus.
  3. Check that all of the colours you see look natural.
  4. Colour-fringing should be minimal (look for yellow/purple fringes around pale objects or telegraph poles, wires and the edges of buildings).
  5. Check the close focus – it may be better or worse than the quoted distance.
  6. If you wear glasses, keep them on when testing products.
  7. Make sure you are happy with how the instrument feels in your hands. Would you be willing to carry it for hours on end?
  8. Check the guarantee.
  9. Choose what works for you.

What are the different parts of binoculars?

Dioptre adjustment

This compensates for any difference between your eyes. Make sure it works (ask the seller how to do it), and that it can be locked into position or is stiff enough not to move once set.

Rainguards 

These cover the eyepieces to protect them from the elements (and crumbs from your picnic lunch).

Eyecups 

These usually twist up and down, often with intermediate positions. Check they stay in position and don’t wobble. If you wear glasses, wind the eyecups down to ensure you can see the whole field of view.

Tethered objective covers

When supplied these attach to the barrels and sit on the ends of the objectives.

Central hinge 

This should be stiff enough to hold position. Adjust it so you see one clear circle.

Focusing wheel 

Make sure you can reach this comfortably, and are happy with both how much ‘travel’ there is and how stiffly or smoothly it moves.

Strap attachment 

Ensure you are happy with how your binoculars hang against your body – some pairs don’t hang flat.


What are the different parts of a scope?

Eyepiece

Can be straight or angled. Most zooms have the zoom ring on the eyepiece. Check that it moves smoothly without too much or too little resistance.

Focusing wheel

This protrudes or encircles the scope body. Check as per binoculars. Some also have a fine-focusing wheel, useful at higher magnifications.

Lens hood

This provides physical protection and improves the view in side-lit conditions.

Rotating collar

A useful tool to swivel the eyepiece to watch from awkward positions.

Tripod attachment

Some scopes have a hole for an anti- rotation pin to stop the scope twisting out of position. Useful if your tripod has a pin.


What do the different terms mean?

Chromatic aberration

A blue or purple fringe around pale objects, or around dark ones against a paler background. Also known as colour-fringing, the effect should be kept to a minimum.

Dielectric coating

In most roof-prism binoculars the prisms need a mirrored (often with silver) or dielectric-coated surface. Dielectric coatings transmit more light than silver.

ED/HD/Fluorite

Extra-low dispersion (ED) and high- definition (HD) glass doesn’t split light into its component colours to the same degree as non-ED glass, producing sharper, brighter images. Fluorite is a type of crystal used in optics for its low-dispersal properties.

Exit pupil

The ‘circle of light’ on the eyepiece. Larger exit pupils deliver more light, making it easier to align your eyes with the exit pupils.

Eye relief

The correct distance between your eye and the eyepiece. If you wear glasses, aim for at least 14mm of eye relief.

Field of view

The size of the area you can view, from left to right and top to bottom. Expressed as degrees, or metres at 1,000m. A larger field of view makes it easier to find what you are looking for.

IPD

Inter-pupillary distance – the distance between the exit pupils.

Lens coatings

These reduce reflections, increase light transmission and keep colours ‘true’.

Light transmission

The percentage of light that enters and leaves the optic. Note that quoted figures may be for only part of the instrument.

Phase coating

Used on roof-prisms to fix ‘phase shifts’, giving sharper, higher-contrast images.

Porro/roof-prism

With porros (the ‘old-fashioned’ binocular design) the eyepieces don’t line up with the objectives. With roof- prisms (the modern, H-shaped design), they do. Most binoculars are now roof-prisms. They are tougher and more compact than porros.


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Main image: Couple birdwatching in a forest. © Amy Eckert/Getty