Role of Eye Relief in Purchasing Bird Watching Binoculars

Individuals who adorn glasses are always at a disadvantage when they want to look through binoculars. They are never able to see the complete image when viewing through both lenses. This happens due to eye relief, which can be both long and short where it does not offer the exact image one wishes to view. For binoculars with short eye relief only the centre of the picture is visible. You might have to hold the binoculars far away from your glasses and continually adjust them to get a clear vision. For binoculars with long vision one is able to view the entire image regardless of whether one is using glasses.

What is eye relief?

Eye relief is one of the factors that need to be considered when purchasing a pair of binoculars. It varies according to the design of the eyepiece. Every binocular has a certain fixed distance at which it needs to be placed so that the image being viewed is completely visible. This is known as eye relief and needs to be adjusted before one starts viewing birds with their own pair of binoculars.
When your eyes are placed further away than the ideal distance or eye relief, the outer edge of the picture will not be visible to you. The further away the eye moves part of the picture visible to you also gets smaller.

So if you are planning to buy a pair of bird watching binoculars that you can use along with your spectacles, you need to consider eye relief. If you do not do this, you will not be able to enjoy any bird watching experience with this particular pair.

A pair of binoculars with long eye relief can be used comfortably by individuals who do not require eyeglasses. In such cases the eyes cups can be extended so that one’s eyes are at the correct distance from the eyepiece.

What is the ideal eye relief for individuals using glasses?

If you wear glasses, you require bird watching binoculars with eyepieces that are specially designed for long eye relief. The minimum distance should be 16 mm although binoculars with more than 16mm eye relief can also be used.
For some binoculars the eye relief is equal to or less than 15mm. The eyecups might be twisted down to allow individuals wearing glasses to get closer, however it might not be as close as required which hampers the view of the object. Binoculars of this type are certainly suited for individuals with no glasses, or those who use contact lenses.

The exact distance you require for eye relief depends on the glasses you use. If they are small in size and can be placed close to your eyes, you might be able to manage with a 15mm pair however in most cases the eye relief needs to be more.