Have you ever used someone else’s rifle and found that the scope is shadowy, lacks a clear view, or is difficult to get into a good position of clarity? Optics are great because they allow users to make more precise shots, have tighter groupings, and give positive target identification at longer ranges. Any magnified optic, including binoculars, has an inherently set eye relief.  We are going to discuss eye relief, how it affects shooters, and why it’s important. We will also be discussing what optics it affects, and how eye relief on a scope needs to be a factor before purchase.

What is Eye Relief for Scopes

what is eye relief scope
3 inches of eye relief

Eye relief refers to the distance between the shooter’s eye and the ocular lens (rear lens) of the scope when the full field of view is visible. Let’s break that down a little more, when the shooter’s eye is at the correct eye relief distance, the shooter will be able to view the full field of view clearly. If the shooter’s eye is too far back the field of view will narrow and give a ‘tunnel vision’ effect.

eye relief on a scope
Eye relief too short (eye too far away)

If the shooter’s eye is too close the picture can be distorted as well. Eye relief is a specific, set, inherent phenomenon to that specific optic. There is no changing the eye relief, only the shooter’s position, or the scopes position on the rifle. Eye relief is an important factor in selecting a scope for a specific rifle and purpose.

Why is Eye Relief Important?

Proper eye relief allows for a comfortable shooting experience. If the eye relief is too short, it may require the shooter to strain their eye and press their face against the stock leading to discomfort and affecting accuracy. On the other hand, if eye relief is too long, the shooter may have difficulty maintaining a stable position and keeping their eye aligned with the scope.

A scope with insufficient eye relief can be dangerous, especially when shooting higher caliber firearms. The recoil may cause the scope to hit the shooter’s eye or face under recoil, resulting in injuries known as “scope eye” or “scope bite.”

Adequate eye relief ensures the shooter sees a full, clear image without any vignetting or black crescents around the edges. An incorrect eye relief may result in a reduced field of view or image distortion, which can negatively affect accuracy (as seen in the photo above).

Having proper eye relief means faster target acquisition when shouldering a rifle. If eye relief is too great or insufficient for the shooter’s natural shooting position then the shooter must move their head, or rifle, or slump over the rifle to achieve a clear view.

This comes at the expense of time, and stability when shooting. Have you ever been hunting moving targets? The window to take a shot can close surprisingly fast, and if you’re struggling to achieve the proper eye relief it’s over before it started.

If the eye relief is too short or too great it results in unnatural shooting positions. It will take longer to naturally acquire the target, your body is out of position, and getting back on target takes longer. This is why eye relief is so important.

What Optics Use Eye Relief?

Not all optics are affected by eye relief. As a rule of thumb, eye relief only applies to magnified optics, greater magnification generally means the optic is more sensitive to eye relief. Red dots, holographic, and prism optics that are not magnified are not affected by eye relief.

Types of Eye Relief

Standard eye relief is generally considered to be 3.5-5 inches for standard hunting rifles. This rests on historic precedence and design over the years.

Optics with eye relief less than 3.5 inches are considered short eye relief. We often see prism scopes, and red dot magnifiers fall into this category, generally around 2.5-2.9 inches. This comes with the dangerous of short eye and scope bite as discussed earlier.

Long eye relief are optics with eye relief greater than 5 inches, generally much greater. These optics are typically used for what is referred to as a “Scout mount” where the optic is forward of the rifle’s receiver. This is for the AK boys out there who don’t have receiver mounts.

How to Adjust Eye Relief

You can’t, I’m sorry to be the bearer of bad news. But you can adjust positioning based on eye relief. Before even mounting the scope or buying a scope it is important to consider several factors.

The type of mounting system the intended rifle utilizes is important to make sure you get the right scope, and understanding how much mounting space is available for eye relief. Modern rifles generally utilize a Picatinny top rail for scope mounting on the upper receiver and the handguard. As such, Picatinny provides a large area where the optic can be mounted.

Dovetail mounts are an older style of scope mounts found on older hunting rifles, they are still made today, but less abundantly. Dovetail rails are generally cut into the receiver on a rifle, and require compatible mounts.

Weaver rails are also a common mounting solution that bridges the gap between Picatinny and dovetails. They feature Picatinny on top, but the sides are cut at angles to mimic a dovetail.

Be sure to understand what rail you have, and how much space is available to mount the optic, as this will determine how close/far the scope can be placed from the shooter.

Be aware of the overall length of the stock if the stock on the rifle is fixed. This will affect where the shooter normally shoulders the rifle in a comfortable position. The same goes for adjustable stocks, it is important they are adjusted to a position of comfort the shooter will likely use. The key is finding a scope with the eye relief that allows the shooter to maintain their natural, comfortable shooting position without needing to adjust their head and body.

Finally, be aware of your physiology, meaning height and reach. Find where you comfortable hold the firearm and make an approximate measurement of how far your eye will be away from the scope when mounted.

This is why Picatinny is the best option, as it gives the shooter more space to mount the optic. Most optics have eye relief listed on the box/website.

Achieving Eye Relief Through Mounting

Alright, at this point you selected a scope for the rifle, and understand eye relief, and where the scope should sit on the firearm. Hand tighten the mount and rings and place the scope in the rings. Check if this is the eye relief that works for you comfortably and naturally. If you have found your perfect eye relief than it is time to securely mount the scope and zero the rifle.

Frequently asked questions

What is good eye relief for a scope?

Proper eye relief is specific to the weapon and the shooter, but as a rule of thumb most rifles do best with standard eye relief which is 3.5-5 inches.

Is higher eye relief better?

Not necessarily, comfortable eye relief is the most important factor. Some rifles are limited where they accept scopes, in which case higher eye relief scopes are necessary. In general, higher eye relief allows the shooter greater situational awareness.

Can you adjust eye relief on a scope?

Unfortunately no, but the placement of the scope is adjustable on most modern rifles.

What causes scope bite/scope ring?

Scope bite/scope ring is caused when eye relief is too short for the weapon, leading to the scope hitting the user’s face upon recoil.

Final thoughts

Eye relief is a critical aspect of a firearm scope that significantly impacts the comfort, safety, and overall performance of the shooting experience. Understanding and adjusting eye relief according to the shooter’s needs is essential for a successful and enjoyable day at the range. Remember to always practice proper firearm safety while using your scope.

The opinions expressed in this post are those of the author and do not necessarily reflect the views and opinions of Tacticon Armament.