What is Eye Relief and How It Works?

man looking through binocs

 

If you have browsed or perused any type of optic, you may have noticed one of the specs is called eye relief. Eye relief can be given in inches or millimeters, and is applicable to any kind of optic.  

This includes spotting scopes, riflescopes, binoculars, night vision devices, rangefinders and more. In fact, optics like microscopes even have an acceptable eye relief. What exactly is eye relief and why is it important to know?  

Let’s look at the technical definition. Eye Relief is the distance from the last surface of an eyepiece within which the user’s eye can obtain the full viewing angle. That’s a mouthful, so let’s break it down into plain English.  

Eye relief is the measurement of how far your eyes need to be from the lens to get the full picture. In fact, we think eye relief is one of the most important factors to consider when it comes to choosing an optic.  

 

Why it Matters 

binocular eye relief

If you have an optic handy, you can find out real quick why eye relief is so important. Take the item and hold it at arm’s length. Can you see anything besides a small dot at this range? Likely not. Now slowly bring it closer to your eye.  

Eventually, you will hit a point where the optic is full of light and picture. There will be no dark rings. Now bring it even closer. Again, you will see the picture start to shrink and a dark circle grow around the entire image.   

Proper eye relief gives you the biggest, clearest, and brightest picture possible. If the optic is too far or too close, the dreaded dark circles will form around your image. Now, you may be thinking you can simply hold the optic at proper eye relief and be done with it.  

Unfortunately, this usually doesn’t work. That is why you need to do your research into eye relief before you purchase an optic. In fact, there are a number of crucial factors you need to consider. 

 

Eye Relief On Spotting Scopes, Binoculars, and Rangefinders 

spotting scope eye reliefThese three optics essentially do the same thing, but in different ways and for different tasks. However, each of them has the goal to magnify an image to give you a clearer picture of what’s in front of you. 

The main differences between these devices are their ranges, and where they can be used to deliver a clear picture. Rangefinders often top out at 6x, binoculars can go a little further, and spotting scopes can go a lot further for long-range viewing 

When using binoculars and rangefinders, you may just be doing a quick scan. If so, a little black on the sight picture isn’t a major deal. In fact, it is highly likely you will experience some minor black while scanning or moving.   

With a spotting scope, the viewing is more deliberate. Since the scope is set up on a viewing platform, the eye relief is often perfect the entire time. Just remember that the longer you are viewing, the less acceptable deviation you will have for eye relief. 

 

What is Long Eye Relief?   

Long eye relief is a specific measurement that has to do with these devices. When you see companies advertising long eye relief what they are saying is you can be a little further from the lens and still use the optic as designed.  

Long eye relief binoculars, spotting scopes, and rangefinders are intended for use with eyeglasses. Eyeglasses create a little extra distance. So without the compensation of an extended eye relief device, you will have a slight black ring distorting your picture.  

Now, you non-glasses wearers maybe be thinking this is not your issue. Maybe it’s not, but maybe it is. If you are a shooter using any of these devices, you will likely be wearing eye protection. Remember to keep that in mind when choosing an optic.  

 

Eye Relief On Firearm Scopes 

Man with RifleFirearm scopes are their own unique breed when it comes to eye relief. Eye relief is critical on a riflescope, because you have a limited field of view and any decrease in it will make seeing your target difficult.  

Some optics have no eye relief and can be used as close or as far from your eye as possible. These are basically 1x red dot optics and can be placed anywhere on a gun. Red dots aren’t necessarily a concern when it comes to shopping for eye relief.  

 

Standard Eye Relief 

The standard eye relief for most riflescopes is 3.5 inches. This measurement is a solid choice for most rimfire and standard centerfire rounds. Standard is the most common option for guns at .308 and below, and is perfect for shooting across relatively flat terrain with mild recoiling rounds.  

 

Long Eye Relief 

Long eye relief with a riflescope is right around 4.5 inches. This extra inch is to compensate for the heavy recoiling rounds. These powerful rounds can give you a nice black eye if your eye relief is too short.   

These scopes are also great if you are going to take uphill shots. As you aim upwards, the space between your eye and the scope is diminished. They are perfect for calibers in the Magnum range, like the 300 Winchester Magnum.  

 

Longer Eye Relief   

Some scopes are designed to be both magnifying and used with powerful handguns. These extremely long scopes are sometimes called scout scopes, or handgun scopes. They are made for specific weapons and can have an eye relief of anywhere from 7 to 10 inches.  

Longer eye relief was created for platforms that either cannot traditionally mount a scope, or simply aren’t designed for a scope in the first place. They are popular on military surplus guns that feature open actions, which make mounting a standard or long scope challenging. 

 

Find Some Relief 

Eye relief is a simple concept and one you should certainly pay attention to, because it determines how well you see your target. If you don’t fully understand the concept, you may end up screwing yourself over.  

To figure out the best eye relief for you, test a few optics. Find what is most comfortable for you and your eyewear situation. Then, plan appropriately. This way, you won’t get a black eye from the 300 Winchester Magnum you’re packing!  

 

What is Eye Relief and How It Works?
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Travis Pike
Travis Pike is a former Marine Machine gunner who served with 2nd Bn 2nd Marines for 5 years. He deployed in 2009 to Afghanistan and again in 2011 with the 22nd MEU(SOC) during a record setting 11 months at sea. He’s trained with the Romanian Army, the Spanish Marines, the Emirate Marines and the Afghan National Army. He serves as an NRA certified pistol instructor and teaches concealed carry classes

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