Optics Buying Guide

Whether you are looking for a pair of binoculars or a scope, let our handy guide help you choose the perfect optic for your needs. A lot of your buying choices may come down to personal choice, such as how it feels in your hand or what purpose you have in mind, but here is an overview to help you.


Binoculars are usually hand held devices made up of two small telescopes which allow you to view distant objects. These produce an image with a greater impression of depth, i.e. a three dimensional image, made up from two images – one from each telescope.


Spotting scopes are a single telescope which really require a tripod due to their size. They are referred to as spotting scopes or field scopes to differentiate them from an astronomical telescope. Spotting scopes tend to have much larger magnifications than binoculars and much larger objective lenses.



Binoculars and scopes all follow a very similar and simple numbering/naming system. i.e. RSPB 8 x 25 Rambler binoculars have a magnification of 8 and an objective lens diameter of 25mm.

Scopes are very similar, but some have variable/zoom magnifications, or allow you to choose an eyepiece with your chosen magnification. For example, the Hawke Endurance 16-48×68 Spotting Scope has a variable magnification of between 16x and 48x, and an objective lens 68mm wide.


Objective lens

This is the lens/lenses that you see on the front of the binocular or scope. The larger this lens, the more light can be gathered and the brighter the resulting image. The higher the magnification, the more light is required, which is why scopes use much larger lenses.



How much bigger the object will appear to you when looking through the binocular/scope. Large magnifications require lots of light to achieve a clear image. The higher the magnification, the more difficult it becomes to stabilise the image. This is because any shake or movement is also magnified by that amount.



Brightness refers to how much light can be gathered. For the clearest, most colourful image, both necessary when trying to identify wildlife, you want as higher a brightness as possible. You can roughly assess brightness by dividing the diameter of the objective diameter by the magnification. More expensive binoculars/scopes use precision lenses and special lens coatings to ensure more light passes through the lens and therefore increases brightness. When looking at model specifications, the higher the brightness number, the brighter the image will appear.


Field of View



This is the “width” you will see when looking through the optic. When tracking an object, such as a bird, a wide field of view will make following a moving object much easier. Field of view is measured in degrees, and is calculated as the width in metres or feet that you will see 1000 yards/metres away i.e. Hawke Endurance 8×42 binoculars have a field of view of 388ft / 129m, whereas Hawke Endurance 10x 42 have a field of view of 304ft / 101m.


Close Focus

If you also want to look at plants, dragonflies or other subjects which are nearer to you, you need to look for a model with a close focus of about 3m or less. Generally, 8x binoculars offer closer focus than 10x.


Lenses and lens coatings

The lenses and coatings used within the binoculars/scopes are key to the quality of the final image as every time the light passes through a lens, or is reflected off an internal prism, there is the chance of degradation. Manufacturers use a series of coatings and extremely precise optical lenses to preserve as much light as possible, resulting in a sharp and accurate image. Models with ED (Extra-low Dispersion) lenses, use special glass in the lens elements to improve colour accuracy.


Eye Pieces and Eye-Cups

If you wear glasses, you can usually keep these on whilst using optics of any kind, but in order to get the most from your binocular/scope, you will need to choose a design with twist-down eyecups. This is so you can wear your glasses and still achieve the same “eye relief” as non-glasses-wearers. This is simply the distance between the eyepiece lens and your eye. Too much eye relief (distance) will result in vignetting (darkening of the edge of the image) and a potentially distorted view.


Many binoculars have a dioptre adjustment. This is to compensate for any differences between your eyes and calibrating your binocular to your eyesight will result in more accurate focussing and a better image.

Many high end scopes are sold as a separate body and interchangeable eye piece. This allows you to tailor the scope to your needs, whether the magnification, brightness, size or weight is a key factor.




Digiscoping is using a digital camera (whether a compact, SLR/CSC or even smart phone) to take a picture through a scope. In the case of DSLR’s or CSC’s, the scope becomes your camera lens using a special “T Adaptor” designed to work with your brand of camera and scope.



Generally speaking with optics, the higher the price, the more features, such waterproofing, fog proofing, ED glass, better lens coatings, more complex lens elements, higher quality body materials, precision engineering, etc.

However, there is a binocular or scope for every budget and type of activity you have in mind. We really recommend trying and comparing some models in-store to see which will suit your needs the best. Our friendly, knowledgeable staff will help you find the perfect fit.

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