Binocular Eye Relief When Wearing Glasses

If you are in the market for the best binoculars for birding and plan on wearing your glasses with binoculars, you need to know about binocular eye relief when wearing glasses. This article will focus on eye relief and why long eye relief binoculars are the best birdwatching binoculars for people with glasses.

Eye relief is the distance from the eyepiece lens edge to the point of focus (where you want to place your eyes). Binocular eye relief when wearing glasses should be at least 16mm. This is because a long eye relief will accommodate the space that glasses will occupy between the ocular lens and the point of focus.

To clearly see a full image when looking through binoculars, you will need to position your eyes a certain distance away from the edge of the ocular lenses. If you are wearing eyeglasses, they may get in the way.

The topic of eye relief is a meaty one and can get kind of technical. But no worries – In the following sections I’ll explain everything you need to know about binocular eye relief and binocular eye relief for eyeglass wearers. I promise to make it as simple as possible, with nice images and videos.

By the time you finish reading, you will know how to select the binoculars with the best eye relief for your needs, as well as how to adjust the binoculars to obtain the best image.

(And, if you want to just skip to the article where I tell you which binoculars I think are the best all-around binoculars for people who wear glasses, you can do that too!)

The Importance of Understanding Eye Relief in Binoculars If You Wear Glasses

Can you use binoculars with glasses? Absolutely – and with splendid results. But you will need to purchase binoculars with long eye relief. The correct binocular eye relief will play a big part in your viewing pleasure and your binocular purchase.

So, what does eye relief mean? When you use binoculars, there is an optimal distance from the edges of the ocular lenses where you will need to place your eyes so that you can obtain a nice full clear image. That distance is called eye relief. But, if you wear glasses, your glasses may get in the way.

That is, as you bring the binoculars to your eyes, the thickness of the glass frames may not allow you to place your eyes at that perfect distance from the ocular lens edges. The eye relief will be too short.

In the image below, the red arrow shows the length of the eye relief. In the depiction on the left, the woman is trying to move her eyes forward so that they align with the tiny red ball (where she needs to place her eyes to get the best image) but notice that her glasses are in the way.

In the depiction on the right, where there is long eye relief, she can easily move her eyes forward.

So how do we get long eye relief? We use binoculars with a long eye relief length and we also adjust the eyecups. Eyecups are moveable devices on the edges of the ocular lenses.

Retracting them (twisting them down or pushing them in) will result in longer eye relief. This will provide more space for your eyeglass frames so that you can position your eyes at the correct distance from the ocular lenses.

What is Eye Relief on Binoculars, and How Does It Work? – Binocular Eye Relief Explained In Detail

To understand binocular eye relief in a bit more detail and how it works, we first need to understand the very simple concepts of eyepoint and point of focus. It might help to first discuss how light travels down a binocular and exits to form an image.

How Light Travels Through a Binocular
Look at or think about a pair of binoculars, with its two very big objective lenses on one end, and the smaller ocular eyepieces (where you place your eyes) on the other end. Have you ever thought about how an image is formed?

Let’s have a look at the interior of this Porro prism binocular. The gold arrow shows the path of the light that enters the objective lenses.

The job of objective lenses is to collect light. Light enters the objective lenses of the binocular and travels through the interior lenses and prisms until it exits the eyepieces. The light beam that exits the eyepieces and forms the image actually comes into focus a short distance from the edge of the eyepieces.

Eyepoint (or Point of Focus)

The point at which the light beams come into focus beyond the eyepiece edge is called the eyepoint or point of focus. Just imagine the eyepoint as a point of light, floating in space, a few millimeters in front of the eyepiece.

If it helps, imagine that you are looking through the binoculars at a Northern Red Cardinal. The light enters the objective lenses, flips and rotates around the lenses and prisms, and then exits the oculars. Just imagine that the focused image of the Cardinal is floating in space at the eyepoint.

This is where you want to place your eyes – right at that point of focus. Right at the eyepoint, to get that perfect image of that Cardinal or American Robin as he feeds on worms, insects, and berries, or prances about in a fountain. Or maybe it’s a White Breasted Nuthatch you have set your sights on or a Carolina Wren. (Yes, I am a bird nut).

Now let’s talk about binocular eye relief when wearing eyeglasses and how it relates to the eyepoint. (Again, the topic of eye relief is super important if you wear glasses when using binoculars since the wrong eye relief – one that is not long enough – will negatively impact your viewing experience.)

So, again, what is eye relief? Eye relief is the distance from the ocular lens to the eyepoint or point of focus. It’s where you need to place your eyes to get the best viewing experience. And, again, placing your eyes at the point of focus will give you a great viewing experience.

The video below on “Understanding Binoculars: Eye Relief” is excellent.

But if your eyeglasses are in the way, you might not be able to get your eyes close enough to that point of focus. Your eyeglass frames and lenses will be at the point of focus instead of your eyes.

Yes, the distances we are talking about are teeny tiny so something as small as an eyeglass frame can make a world of difference.

The image below is an exploded view to clearly show the relationship between eye relief and the eyepoint. In real life, the user would be holding the binoculars much closer to her face – the eyepiece lens would be much closer to the eye, and so the red line depicting the eye relief length would be shorter.

What Is The Best Binocular Eye Relief If You Wear Glasses?

The good news for eyeglass wearers is that you don’t need special binoculars if you wear glasses. Again, this is because many binoculars offer longer eye relief lengths and as noted above longer eye relief is better for people with glasses.

So, is it enough just to be guided by the mantra “longer eye relief is better for eyeglass wearers” or is there more to it? I mean, what is GOOD eye relief for binoculars? How much eye relief do you need?

If you are looking for the best binoculars for birding and you wear glasses, a good eye relief length will be 16mm eye relief or more. That’s the general guideline (some people even say anything over 14 or 15mm is enough but I think that’s cutting it too short).

To be on the safe side, when looking for the best binoculars for glasses wearers, an eye relief length of 17-20mm is recommended if your eyeglass frames are on the thicker side or if you have strong features, like a strong brow and prominent cheekbones.

BTW, since eye relief length will vary across different manufacturers and binocular models when you purchase binoculars it’s important to make sure the eye relief is clearly stated. You’ll find that most eye relief lengths range from 5-20mm, averaging out at about 12mm.

(Make sure that you check out my top-4 recommendations for the best binoculars for eyeglass wearers.  They all have great eye relief for people who wear glasses.   I have a favorite and I’ll tell you why I think they are the perfect all-around binoculars.)

Now that we have learned all about eye relief, let’s talk about how we can make eye relief on a particular pair of binoculars longer and shorter .. it’s the eyecups!

What Is the Best Type of Eyecup For Eyeglass Wearers: Twist-up Eyecups vs Fold-Down Eyecups

Again, there are 2 types of eyecups for binoculars – those that fold up and down…

… and those that twist up and down (the twist-ups often offer more eyecup position options).

Twist or fold down to get longer eye relief, and leave the eyecups extended for shorter eye relief.

These are the main things you need to know about both eyecup types. These differences are important if you want to obtain sufficient binocular eye relief when wearing glasses (though I’ll cut to the chase and tell you that I recommend the twist-ups!)

Fold-down eyecups:

• are an older” style eyecup, and are slowly being phased out
• are simpler and cheaper to manufacture since they are made of rubber
• are often (but not always) found on less expensive binoculars
• can be difficult to fold and sometimes pop back up on their own
• have two positions – up and down
• are prone to wear and tear, over the years ripping along their folded rubber edges
• are primarily found on Porro prism binoculars

Some users like folding eyecups since they cut down on stray light and the soft rubber can be very comfortable to rest your brows against.

Twist-Up eyecups:

• are more modern than folding eyecups
• are more expensive since they cost more to manufacture
• are often (but not always) found on more expensive binoculars
• may offer multiple positions you can set them in (BIG ADVANTAGE!)
• if of greater quality, will provide resistance and stay in position when resting your eyes against them
• may allow users to lock the position of the eyecup after it has been set
• are primarily found on Roof prism binoculars

If we look at the respective pros and cons of folding eyecups vs Twist-up eyecups, and the role that they play in binocular eye relief when wearing glasses, it’s clear that Twist-Ups are preferred. This is especially the case when twist-ups have multiple settings and are of higher quality.

Even though twist-up eyecups are more expensive, the added cost is worth it.

How to Use Binoculars with Glasses (Finding the Perfect Eyecup Position)

If you plan on wearing your glasses with binoculars, you may not know exactly how to use binoculars with glasses. I have good news – using binoculars with glasses is super simple. No gymnastics are required.

You will look through the binoculars like people without glasses do. However, you will first need to adjust the eyecups of your binoculars to get the best viewing experience.

You simply retract your twist-up eyecups all the way down or fold down your folding eyecups.

As for how close you bring your eyes to the eyecup edges, you will easily figure it out. After you have adjusted the eyecups, just start by placing your eyes a short distance from the edge until you get a full field of view.

There should be no shadowing around the image. (This shadowing effect is called “vignetting” and I discuss it in the section below).

You may need to move your eyes slightly closer to or away from the eyecups to get the best view. Just take your time.

Also, depending on the visual issues and needs of each user, the ideal eyecup position may fall somewhere between full extension and retraction. So you can play with the position of the eyecups as well.

For example, if you have very thin eyeglass frames and a flatter profile, you may find that just partially retracting the eyecup works best for seeing a full field of view without any shadowing.

Even the weather may impact the eyecup length you select – on a cold morning, resting your warm face on fully extended cold eyecups may result in fogging. Better to partially retract them and hold your face further away from the edge of the binocular.

As for how you hold the binoculars, just hold them so they are comfortable. Some birders like to rest them against their brows to steady them so they don’t move around too much.

(BTW, you may also be wondering “Do I NEED to wear my glasses with binoculars?” If you have astigmatism, yes. But if you are near or far-sighted, you can choose to keep them on or take them off. If you take them off, make sure to readjust the eyecups by extending them.)

What Happens If Binocular Eye Relief Is Not Correct?: Vignetting

If binocular eye relief is too short or too long, shadows will be seen around the edges of the field of view. This is called vignetting.

In binoculars, if vignetting occurs when eye relief is too short, the eyes will be positioned behind the point of focus.

As a result, there will be a significant decrease in brightness around the edges of an image, while the center of the image will remain bright. The periphery of the image will appear as a black ring or shadow.

When vignetting occurs, you will also have a reduced field of view since the edge of the image will darken. For example, when viewing a bird you might miss the beak, the feet, and the tail.

As you know by now, if you are looking for the best birding binoculars, and plan to wear glasses with binoculars, vignetting can easily be remedied by purchasing binoculars with a longer eye relief length, and also retracting the binocular eyecups.

This will increase eye relief length so that eyes are positioned at the point of focus.

The representation below is an exaggerated view of vignetting (I created this to get the point across) – we can see that when the eyes are positioned behind the eyepoint, a blackened ring appears around the periphery of the image. In real life, the ring might look much like a very dark shadow.

To understand the vignetting effect, try pulling the binoculars away from your face, little by little. The more you pull, the more vignetting, and so the less field of view, you will experience.

Interestingly, too much eye relief can also be an issue. When your eyes are positioned closer to the eyepiece than they should be, the eyepoint actually exists behind your eyes. As a result, you will also see vignetting, but in the shape of a crescent shadow.

Final Words on Binocular Eye Relief When Wearing Glasses

This has been a fun article for me to write since it brought back some memories of using binoculars years ago, as a newbie. When I first started using binoculars, I didn’t know I was supposed to retract the eyecups. I don’t even think I knew that you could retract them!

Also, I didn’t know anything about eye relief. I may have heard someone mention it but I probably thought it had something to do with dry eye! My naive assumption of where you were supposed to place your eyes was “as close to the binocular as possible”.

I’ve since observed many novice birders – especially kids – who wear glasses struggling when they first use their binoculars.

They may wonder “Yikes, how exactly do you look through binoculars with glasses? Why doesn’t the image look good?!” They don’t realize that to get the best binocular eye relief when wearing glasses, you need to adjust the eyecups.

I’ve also observed birders who don’t need to wear glasses and try to forcefully place their binoculars directly against their eyes, almost pressing the binocular eyepieces into the ocular cavity beneath their brows.

Again, I once did this as well and wondered why the image was partially obscured by shadowing (it’s because my eyes were in front of the point of focus). I knew little about how to get the best binocular eye relief when wearing glasses.

In closing, I hope you’ve learned enough about binocular eye relief when wearing glasses so that you are well-equipped when you search for the best binoculars for people with glasses! I have selected 4 great pairs of binoculars for you, starting with what I think are the best all-around pair of binoculars if you wear glasses.

Please remember that if you plan on wearing your glasses when using binoculars, it’s important to select high-quality long eye relief binoculars (as much as you can comfortably afford) as well as twist-up eyecups that will allow you to fine-tune the distance you place your eyes from the edge of the eyepiece.

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