Eye Relief in Binoculars: Comprehensive Guide

Do you know the reason behind your eye strain while viewing through binoculars?

It is because of eye relief. Without proper eye relief adjustment, it may become impossible not to cause strain at your eyes while using a pair of binoculars.

The eyepiece lens is the one closest to your look. Good eye relief is essential since if your eye is too tight or too far away from the eyepiece, you will lose the picture’s edges. As such, A binocular’s eye relief is simply the distance your eyes must be from the eyepiece for you to obtain an entire field of view. People who wear eyeglasses need to get binoculars with long enough eye relief to accommodate their frames. Otherwise, they will find it difficult to see the whole picture.

In the field of view, eye relief plays a crucial role. It carries the responsibility of protecting both eyes from impact and shock. Basically, for a large area of the picture and clear image, eye relief contributes significantly.

When using a binocular, you may experience eye fatigue due to straining your eyes, though, which may be why people claim eye fatigue after observing through binoculars for just a short time. Several eyepieces come with eyecups which can be extended or retracted depending on the level of eye relief you require.

The rest of the article shall solve all your doubts and issues related to eye relief for glasses wearers and non-glasses wearers and stick around until the end to view the FAQ.

Difference between eye relief and eyepiece?

A common misconception is a difference between eye relief and eyepiece. The lens fixed on the binocular’s front side is known as an eyepiece; this is the binocular focus.

Furthermore, eye relief is a segment in binoculars that divides the pupil and eyepiece lens. In contrast, eyepieces and eye relief are not the same. Eye relief only guarantees the large image, while the eyepiece lens only ensures the image quality.

Additionally, eye relief protects the eye from direct impact; however, an eyepiece only displays a clear image. 

Choosing The Best Eye Relief

Binoculars are among the optical instruments that offer adjustable eye relief. Binoculars with an eye relief of 16mm are comfortable for eyeglass wearers. That same binocular wearer would have to strain their eyes to see the entire field of view if the eyecup was twisted out.

Due to the extended eyecups, some eye relief is lost, and you are left with less than the desired eye relief. The eyecups need to be adjusted so you are comfortable and can see everything in your field of vision, regardless of whether you wear glasses.

Binoculars have eyecups with multiple adjustable positions that allow more flexibility for viewing, give comfort and eye safety for both glass and non-glass wearers. Wearers of glasses should keep the eyecups retracted as much as possible. In contrast, non-glass wearers can keep their eyecups extended.

Relation Between Magnification and Eye Relief

Increasing magnification will reduce the field of vision, in turn reducing eye relief on your optical device. That’s how optical physics works — it’s a trade-off. In high zoom, there is minor eye relief. In low zoom, it is more eye relief.

If you have variable zoom binoculars, search for the maximum view area and minimise the minimum view area. If you have fixed magnification binoculars, adjust your eyecups for best viewing.

Best Eye Relief- Long or Short?

Most binoculars come with short eye relief. It is unavoidable to have one, but what is essential is what eye relief is suitable for the person who wears them. 

It is crucial to get the correct eye relief because when your eyes are not within the recommended eye relief distance, you’ll run into vision problems either too close or too far. Let us see which one is the most convenient. 

Long Eye Relief

The long eye relief of binoculars is typically 20-24 mm, allowing for less significant distance for those who wear glasses and providing more comfort to use since the eyepieces won’t have to be directly on your eyes, which helps in reducing eye strain. Wearing spectacles or not, a binocular with long eye relief will show you the whole image no matter what. However, several binoculars don’t have long eye relief; it mostly comes with branded binocular only.

Short Eye Relief

Short eye relief is an issue that primarily affects those who wear glasses. For those without glasses, anything less than 13mm is considered short eye relief. But you might find that you are straining your eyes.

Could the eye relief in binoculars be adjusted?

Today, binoculars have extendable eye relief, which means that they can be adjusted to suit the wearer’s eyeglasses. A binocular with a 16mm eye relief size is one such example.

If your eye relief comes with a default 13mm size, you then extend or turn the knob to increase it. Conversely, if you wish to decrease its power, turn the knob in the (-) direction. This way, you can adjust its intensity as you please.

Good Eye Relief For Glass Wearers

When you look through binoculars and glasses for a closer look, you may not be able to watch comfortably. In this case, you will be better off choosing 16mm to 24mm eye relief binoculars.

Good Eye Relief For Non-Glass Wearers

We can have an ideal eye relief of 10mm to 16mm in ordinary binoculars because we do not need eyeglasses. 

It is essential to choose a lens size between the designated range for a comfortable and sharper image.

Questions you Might Have:

What is eye relief? A binocular’s eye relief is simply the distance your eyes must be from the eyepiece for you to obtain an entire field of view.

What is the difference between eyepiece and eye relief? When using binoculars, the eyepiece determines the distance between the pupil and the lens. At the same time, the eye relief measures the distance between the iris and the lens.

Can I use binoculars without my glasses? Would I need an eye relief of 16mm or greater? Modern binoculars can be used without glasses. The binocular can zoom in and out to match your eyesight. However, eye relief of lower than 16mm provides less view and can cause strain.

Does using 12mm eye relief with glasses causes eye strain? A 12mm eye relief can be tough to use with glasses as it will reduce the field of view and cause eye strain.

Is it possible to purchase extra eye relief if my binoculars do not have 16mm? Eye relief is not something that you can buy; it’s built-in with binoculars.

Does long eye relief work only for people who wear glasses? No, everyone can use long eye relief.; It increases the view area and becomes compatible for people with glasses.