Binoculars Eye Relief – All you Need to Know in 2022

By Richard

Have you ever struggled to get a clear image and noticed through binoculars that the corners are blurry? It’s not only you, but many optics users suffer through this due to smaller eye relief of their optical instruments. Especially those who wear glasses face this problem as the glasses on the eyes reduce eye relief.  Are you confused and don’t have any idea about eye relief in binoculars? Don’t worry, let’s dive deeper to know all about binoculars eye relief.

What is Eye Relief for Binoculars?

When a person uses binoculars, there remains a distance between the eyes and the eyepiece. This distance between the eye and eyepiece is known as eye relief. It is responsible for improving and reducing the comfortability of using binoculars. Every optic has different eye relief.

What is the difference between eye relief and eyepiece?

People usually get confused between the eye relief and eyepiece of binoculars. Eye relief is defined above and is the distance between the eyes and the ocular lens. The eyepiece is a lens that helps in magnifying the image produced by the objective lens.

In simple words, the objective lens captures light and makes a primary image. Then the eyepiece magnifies the images and shows them to the human eyes. How much an eyepiece will magnify the image majorly depends on the focal length

Eyepieces are used in almost all optical instruments like microscopes, telescopes, binoculars, etc. Another name used for eyepieces is “ocular lens”.

What is a Good Binoculars Eye Relief?

There is no fixed size in binoculars’ eye relief. Optics with a variety of eye reliefs are available in the market. Usually, the eye relief ranges from 10 mm to 20 mm, and anything below 10 mm is considered the worst distance between the eye and eyepiece. 

Short eye relief

Anything between 10 to 15 mm of eye relief falls in the shorter eye relief category. We don’t recommend you to choose optics with shorter eye relief. 

Long eye relief

A size above 20 mm is considered long eye relief. Choosing long eye relief is always a wise decision. All the top-quality binoculars come with long eye relief. 

Disadvantages of smaller eye relief

Decreasing eye relief is directly associated with image clarity. Binoculars with shorter eye relief give the images with faded or blurry edges. The image will be zoomed and optimally focused at the center.  Anything which will be in the center of the image will be clear. The corners of images will not be clear due to less eye relief.

 How eye relief affects the glasses wearers?

The glasses on the eyes further decrease the distance between the eyes and the eyepiece. It means glasses on the eyes decrease eye relief. Reduced eye relief size affects the image quality and the user suffers from blurry corners of the image.

eye relief for glasses wearers
Eye relief for glasses wearers

The issue worsens when the user with glasses due to weak eyesight chooses shorter eye relief. Without glasses, he won’t be able to see the objects. With glasses, he will see the image with distorted edges due to reduced eye relief.

What is a good eye relief for glasses wearers?

As mentioned above anything above 20 mm is considered long eye relief. Keep in mind that if you wear glasses then always look buy binoculars with at least eye relief of 18mm

If you’ve weak eyesight and you opt for a binocular with shorter eye relief, then you will end up regretting your purchase as it won’t give you a comfortable viewing experience. 

Is relief important for those who don’t wear glasses?

Well, it may not be as important as it is for glasses wearers but it holds its significance to some extent. The long binoculars eye relief is important for a comfortable viewing experience. The more distance between the eyes and eyepiece, the easier it will be to see the view through binoculars.

We don’t buy optics every day; instead, we buy them once a year. Is it confirmed that your vision will always be as good as it is now? Obviously, No 

So purchasing binos with a lengthy eye relief will benefit you in two ways: it will provide comfortable viewing and better images when you wear glasses.

Can I adjust the eye relief power in binoculars?

Almost all the premium hunting binoculars come with the feature of adjustable eyecups. The adjustment in eyecups helps in increasing and decreasing the eye relief of binoculars. 

The main function of eyecups is to prevent outside stray light from entering the eyepiece. If the stray light succeeds in entering the eyepiece of binoculars, the image will be destroyed

These rubber eyecups are also helpful in adjusting eye relief. Rotating the knob in positive and negative directions increases and decreases eye relief respectively. If you wear glasses due to weak eyesight, make sure to rotate the knobs in a positive (+) direction to get a longer eye relief.

Final thoughts on Binoculars Eye relief

It does not make sense to use optics that give you distorted images due to smaller eye relief. Making slight mistakes in choosing the right eye relief can ruin your money. Don’t purchase optics whose eye relief is less than 15 mm. In case you wear glasses due to poor vision, always choose binoculars over 18mm.