Getting the right optical kit for bird watching or survey work doesn’t have to be complicated of break the bank, in spite of the initially alarming prices of the top of the range equipment. Once you have binoculars, scope and tripod, the rest is for the most part inexpensive accessories. Taking the first step into the optics market is daunting to say the least, especially when confronted with the enormous range available today.

The 3 Steps to Choosing the Perfect Binoculars

At Cley Spy we stock around 180 models of binoculars and over 40 scopes, which is an intimidating prospect to start sorting through for anyone.

By considering a few simple questions it is easy to cut through the sea of model names, numbers and acronyms and narrow the choice down to four or five suitable options.

Here we refer to binoculars, but the same principles apply in general to scopes as well.

How much do I want to spend?

Our binoculars range from around £15 to £2,000 and get better the more you spend. So how much is a good one?

£90-£200 will get you a functional, well built and optically good binocular. It will almost certainly be waterproof and will have a 2-10 year warranty depending on manufacturer.

£1,000-£2,000 will get you the best optics on the planet. You don’t have to be trying to accurately assess the exact subtle shade of yellowy/greeny/greyish brown on a vagrant warbler to appreciate this quality – but you need it if you are.

Which specification?

The most common specifications are 8×32, 8×42 and 10×42 (see “What the numbers mean” below). Which one to choose comes down to personal preference. 10x will make things appear a bit closer than 8x, but 8x will have a wider field of view and be easier to hold steady.

What size and weight?

No-one ever asks us for “big and heavy” binoculars or scopes, but compromises do have to be made. The smallest and lightest “compact binoculars” are typically 8 or 10 magnification with 20-25mm objective (front) lenses. These are pocket-sized but have to sacrifice brightness and ease of use to be so small. 8×32 is a popular specification because it is about as small as you can go without significantly impacting the image quality. However, in the poor light of dawn, dusk and December the brighter image of an 8×42 will be a real advantage.

And that’s about it really! When you have answered these questions you can browse our products with the knowledge and confidence to make the right choice.

What do the Numbers Mean?

On any binocular the specification will be given as one number times (x) another number (e.g. 8×42).

The first number is the magnification (how many times closer an object appears).

The second number is the diameter of the lens furthest away from your eyes (the objective lens).

The bigger the first number, the higher the magnification, the bigger the second number the brighter the image will be.

Too much magnification makes binoculars hard to hold steady and bigger objective lenses makes them heavier to carry around.

Lens Types

Binoculars come in two basic styles: Porro Prism and Roof Prism (see diagram below). The Roof Prism style has become very popular in recent years because it is more compact as well as typically being waterproof, fog proof and filled with Nitrogen gas to keep moisture and dust out.

The more traditional Porro Prism style is bulkier, but usually less expensive. Another feature which is found on many binoculars is the twist-up type eyecups, which are better for spectacle wearers and do not wear out as quickly as the old fashioned foldable rubber eyecups.

Binocular types

Glossary of some of the terms associated with binoculars and what they mean.

APO. Abbreviation of apochromatic. A completely apochromatic lens system corrects all chromatic aberration (colour fringing).

BK-7 and BAK-4 prisms. These are two grades of glass, boroscilicate BK-7 (generally in cheaper optics) and barium crown BAK-4 (delivering better sharpness)

ED, HD, HR. Terms used to denote higher-quality glass models, HD standing for High Definition, ED usually standing for Extra-low Dispersion, and HR standing for High Resolution. These terms are not standardised, one companies standard glass can sometimes be as good as another’s HD. With Leica and Swarovski HD denotes models with fluorite lenses.

Eye relief. This is the distance that your eye should be from the eyepiece lens to get the optimum image. Spectacle wearers often need a longer eye relief when using binoculars with there glasses on.

Nitrogen filled. Waterproof binoculars are often filled with a dry, inert gas (most commonly nitrogen or argon) to prevent internal fogging.

Phase correction. Coatings applied to prisms to reduce dispersion, giving sharper images with better contrast and reduced chromatic aberration (colour fringing).


For further information and advice on choosing binoculars without too much technical jargon please contact us on 01263 740088 or e-mail via the Contact Us page on the Cley Spy website.