What the terminology means and how to use this information to get the right binoculars for you.


Magnification
The standard method of specification uses 2 numbers, such as 8 x 21 - but it is only the first number that is actually the magnification. In this case 8x means that the image is magnified 8 times (or whatever you are pointing the binoculars at will be 8 times closer!)

The second number is the diameter in millimetres of the object lens (the pair of lenses at the 'fat' end of the binoculars that are furthest away from your eye). The larger these lenses the more light they will be able to catch and therefore the brighter the image.

Exit Pupil
The exit pupil is the diameter (in millimetres) of the image on the exit lens (the pair of lenses at the 'thin' end of the binoculars that you put to your eye). The larger the diameter the brighter the image is likely to be.

We display the exit pupil diameter for our binoculars, but you can easily work it out for yourself by dividing the diameter of the object lens by the power (or magnification). In our example of an 8 x 21 binocular 21 / 8 = an exit pupil of 2.6 (also known as the BI or Brightness Index)

Angle of View
This is an indication of the amount of your target that will be visible when you point the binoculars at something. It refers to the angle of the spread of light collected by the object lens.

Doesn't mean a lot? Well, depending on how far away they are, point your binoculars at someone's face and the angle of view determines whether you will see their whole face or just the tip of their nose! Binoculars with smaller angles are likely to catch just the tip of the nose while larger angles will show more of the face.

Generally speaking the greater the power or magnification of a pair of binoculars the narrower the angle of view. A good pair of 8 x 21 binoculars will have an Angular Field of View of 6° to 7°, decreasing to 4° or 5° for binoculars with the highest magnifications.

Field of View at 1000 Metres
Because the Angle of View refers to an angle of spread it means that more of an object will be visible the further away it is. In order to compare like with like we have to choose a fixed distance. This value is the diameter of a landscape that will be visible when the binoculars are used to view an object that is 1000 Metres away.

Eye Relief
This is the maximum distance that your eye can be away from the binoculars without affecting the quality of the image your are viewing. Important for people who wear glasses and don't want to rub their glasses against the binoculars - or should that be 'rub the binoculars against their glasses'?

Near Focus
If you feel you are likely to use your binoculars to view objects close to you, this indicates the minimum distance at which the object will still be in focus. Anything beyond this distance will be in focus, everything nearer will become increasingly blurred the closer it gets.

Roof Prism
A roof prism design means that the lenses inside a pair of binoculars can be in a straight line to give a slimmer, sleeker shape. This can produce binoculars of a more rugged construction, but at a slight optical cost.

Porro Prism
The porro prism design tends to offer a greater perception of depth and an enhanced field of view. Binoculars with this layout can usually be recognised by the traditional 'flared' shape. This shape is probably the one we all imagine when we think of a pair of binoculars!



What are you most often going to be viewing?

For general viewing low to medium magnification is best. Higher powered binoculars will tend to reduce the area in view, make it more difficult to locate the intended object and magnify every slight movement. With high-powered binoculars it can be difficult to keep the image still!

• Vision Binocular - Low power (5x) general purpose binoculars at an extremely low price
• Hunter Binocular - Medium power (7x) high quality porro prism binoculars producing an exceptionally bright image
• Scenic Monocular - Medium power (8x) high quality monocular - A cross between binoculars and a telescope!
• Scenic Binocular 8x - Medium power (8x) high quality roof prism binoculars.
• Scout Binocular 8x - Medium power (8x) high quality roof prism binoculars.
• Scope Binocular 8x - Medium power (8x) high qulaity roof prism binoculars.

For examining distant objects closely, such as birds in distance trees, higher magnification becomes important. Look at our binoculars with 10x magnification.

• Scenic Binocular 10x - High quality roof prism binoculars with good field of view.
• Scout Binocular 10x - High quality roof prism binoculars with good field of view.
• Scope Binocular 10x - High quality roof prism binoculars with good field of view.
• Horizon Binocular - High quality porro prism binoculars with exceptional field of view.
• Panorama Binocular - High quality porro prism binoculars producing a brighter image.

When are you likely to be viewing it?

For daylight viewing an exit pupil value between 2mm - 3mm is ideal.

• Scenic Monocular - Medium power (8x) high quality monocular - A cross between binoculars and a telescope!
• Scenic Binocular 8x - Medium power (8x) high quality roof prism binoculars.
• Scenic Binocular 10x - High quality roof prism binoculars with good field of view.
• Scout Binocular 8x - Medium power (8x) high quality roof prism binoculars.
• Scout Binocular 10x - High quality roof prism binoculars with good field of view.
• Scope Binocular 8x - Medium power (8x) high qulaity roof prism binoculars.
• Scope Binocular 10x - High quality roof prism binoculars with good field of view.

For viewing in reduced light, such as bird watching at dusk or dawn, a higher exit pupil value becomes important. These binoculars are perfect, with a larger object lens to capture more light and produce an exit pupil value as high as 11.8mm (Panorama Binocular).

• Hunter Binocular - Medium power (7x) high quality porro prism binoculars producing an exceptionally bright image
• Horizon Binocular - High quality porro prism binoculars with exceptional field of view.
• Panorama Binocular - High quality porro prism binoculars producing a brighter image.