Wot, no jargon? Cley Spy tells it to you straight.

Cley Spy's latest advert
in the birding magazines

In August 2001 Cley Spy opened in the front half of an old carrot washing barn in Glandford near the

North Norfolk coast, stocked with a handful of binoculars and telescopes. Since then we have expanded to become the biggest independent specialist optics shop in the country, with over 180 different models of binocular, over 40 telescopes and our second hand stock all on shelf to be tried and tested. Over the years Cley Spy has become the place to visit for the best advice and choice of specialist nature watching equipment.

Whatever your budget we will always give you our honest and frank advice and explain the acronyms and technical terms that you are likely to come across.

The impressive view from the back of our Glandford shop
over fields managed for conservation.

We regularly get visitors travelling from all over the country because the range of stock, viewing facilities and expertise we can offer are the best around.

Even if you can't make to us in person we are always available to offer advice over the phone or via the website.

Here are some of the terms often associated with binoculars and telescopes with a brief explanation of what they mean.

APO. Abbreviation of apochromatic. A completely apochromatic lens system corrects all chromatic aberration (colour fringing). Leica's APO-Televid scopes also have fluorite lens elements.

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)

Digiscoping. This is the general term for taking digital photographs through a scope. This can be done with almost any kind of camera including smartphones, but some work much better than others. For more information on digiscoping click here to read our blog on the subject.

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. Spectacles wearers often need a longer eye relief when using binoculars with there glasses on.

Nitrogen filled. Waterproof binoculars and scopes 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).

Roof prism and Porro prism.

These are the two widely available types of binocular. It is simply the type and layout of the prisms in the barrels (see picture). This has some minor impacts on the image, but the big difference is the smaller overall size of a roof prism compared to a porro prism of the same specification.

Spotting scope, fieldscope and telescope. These terms are often used interchangeably or just shortened to 'scope' when referring to birdwatching telescopes.

Birdwatching telescopes vs. Astronomical telescopes. Birdwatching scopes are almost without exception of the refracting type (using lenses and prisms) whereas astronomical scopes can be both refracting or reflecting (using a combination of mirrors and lenses). As a rule birdwatching scopes can be used for basic astronomy, but astro scopes do not work well for birdwatching due to not being waterproof and producing an inverted image. Astro scopes are also relatively big and heavy.