All about eye relief: choosing binoculars and spotting scopes for glasses wearers

There are many models of binoculars and spotting scopes on the market suitable for use with spectacles or sunglasses. These optics that can be used while wearing glasses offer you enough distance between your eye and the ocular lens to ensure that you benefit from the widest field of view and in great focus.

This distance between the eye and the eyepiece is called eye relief. The most important thing to know about how you use glasses with binoculars is that the eye relief has to be just right for you.

If you don’t have the correct eye relief, you will miss out on the full field of view. Here we will explain why eye relief is important and how to choose the correct length of eye relief for your situation.

What is eye relief in binoculars and spotting scopes?

Eye relief distance refers to the gap between the ocular lens on the eyepiece (the glass closest to your eye) and your eye itself. It’s important to get eye relief right to preserve the full width of your field of view. In addition, the correct eye relief will make sure the image is all in focus.

Why is eye relief important?

Eye relief is an especially important measurement for people who use glasses. In this case, you will need a greater eye relief than people who do not wear glasses.

This is because your eye will be a bit further from the ocular lens of the binoculars or spotting scope because the glasses will be in between. If you don’t have the correct eye relief, you will miss out on the full field of view.

Is more or less eye relief better?

If the eyepiece is too near to your eye, then the image will be unclear around its edge. Your eyes will get tired quickly. They may be inclined to blink more than usual.

But if the ocular lenses are too far from your eye, the image will just shrink into the centre. Eye relief that is too short gives a distinctively poor view. It will cause the view to seem as if you are looking down a tube, like tunnel vision.

With incorrect eye relief, you’ll also find that you are constantly trying to move the binoculars or spotting scope. It can be tiring to keep having to move them into a suitable position. This might mean you are bumping them into your brow or against your glasses, and still getting a distorted image!

Eye relief has to be just right for you. Fortunately, with the right optical device this can be achieved easily.

What is the best eye relief for binoculars or spotting scopes?

Your binoculars and spotting scope will work most effectively for you when the eye relief is correct for your personal dimensions.

If you don’t wear eyeglasses, look for a measurement of 9-13 mm. This will allow your eye to be at the right distance for a nice wide field of view.

If you do wear glasses, you can use any spotting scope or binoculars that have the appropriate eye relief distance to fit your needs.

For those people who do wear glasses, choose a measurement between 14-18 mm, depending on the thickness and the distance of the glasses from the eye.

Different glasses, different faces, different eye relief

For wearers of thinner glasses, a comfortable measurement for eye relief is between 14-15 mm.

For those who wear thicker glasses or those that don’t fit as closely to the face, choose an eye relief of 16-18 mm.

If you can find binoculars with eye relief of 20 mm then these will offer the most flexibility.

With this eye relief measurement, glasses wearers can still adjust the eye relief using the eye cups, if necessary, to gel with the style and fit of your glasses.

Do they make special binoculars for people who wear glasses?

There are special binoculars available that have an eye relief greater than 20 mm.

Because your eye is even further from the lens, it can be difficult to ensure that these special binoculars are correctly placed in front of your eye. Your eyes need to be in a position that will give you the best view without black shapes intruding.

Rather than opt for these ‘high eye point’ binoculars, you might prefer to compromise with a pair that has less eye relief. This means you would settle for a slightly narrow field of view that is at least in focus.

Whatever the eye relief, binoculars seem to work best with glasses with flatter lenses rather than, say, wraparound sunglasses.

How do you set eye relief on binoculars and spotting scope?

Standard binoculars might have rubber eye cups that fold back to accommodate glasses. This allows the eye to be closer to the lenses. Now, these types of binoculars are dying out as they are more susceptible to wear and tear.

Increasingly, you will see that many models of optics have adjustable eye cups. These eye cups are fixed outside of the ocular/optical lens and fit into your eye socket.

Eye cups enhance your experience by enabling you to tailor your pair of binoculars to your own eyes, with or without glasses.

Glasses wearers leave eye cups unextended

Glasses wearers would usually want the eye cups unextended, to keep their eyes as close as possible to the optical lens.
These eye cups can be twisted out to extend the eye relief for people who do not use glasses.

Many eye cups can be locked into place. That allows them to be personalized in the right position to suit you.

As well as allowing you to adjust and pre-set your eye relief, eye cups also help shade your eyes from any extra distance while you are viewing.

Is eye relief different on spotting scopes with zoom magnification?

Many spotting scopes have a magnification range, rather than a fixed magnification. This means that the eye relief can vary a little when you zoom in or out.

In some instances, the lower the magnification, the greater the eye relief. And at higher powers of magnification, the eye relief can decrease.

This is not true for all spotting scopes, however. On some spotting scopes, the eye relief remains the same. This is the case, whether or not the magnification power moves up or down in the range.

Summary: why glasses wearers need to be aware of eye relief

If you wear glasses, it is possible to use binoculars or spotting scopes with them. The most important thing to remember when using optical devices in combination with glasses is that you need enough eye relief.

• People who don’t wear glasses will be looking for a comfortable eye relief of 9-13mm.
• People who do wear glasses, need between 14-18mm, depending on the thickness and the distance of the glasses from the eye.

Each instrument can usually be adjusted for an individual’s needs, using the extendable eye cups. There are many models of optical devices on the market that can offer you enough distance between your eye and the ocular lens. This sufficient distance of eye relief will give you the best view of the birds you are watching.

If you have been wondering how to use eyeglasses when birding with your spotting scope or binoculars, then hopefully now the matter is clearer. With this information, you can make an informed decision on how much eye relief your optics will require. For further discussion of whether to wear glasses when birding with options, please see this article > Should I use binoculars and spotting scopes with or without glasses?

Glasses wearers can have just as much choice of spotting scope or binoculars as those who do not wear spectacles. And let’s face it, most people will want the option of wearing sunglasses while viewing through their scopes. Especially on those bright sunny days that are sure to be on their way!

For binoculars with the adequate distance of eye relief for people who wear glasses when birding, check out our list here: The best birding binoculars for glasses wearers

Here are some great choices of spotting scopes that will be suitable for glasses wearers: The best birding spotting scopes for eyeglasses wearers