What is Eye Relief on a Scope


Your hunting partner shows up to the lodge with an extended, deep cut above his right eye. His head is down so that no one would notice the badge of honor.

The mishap goes by many names:

  • Scope Eye
  • Bushweld Tattoo
  • Weatherby Eye
  • Magnum Eye
  • Scope Bite

what is eye relief

Rifle Scope

The distinctive cut is the result of a sharp blow to the brow bone, by way of a rifle scope recoil. Experienced and inexperienced shooters have endured the embarrassment of scope bite. Elite shooters know the importance of proper eye-relief and how to make sure it does not happen to them.


The shooting system, as described by the NRA, includes Fit, Form and Function, and Mounting. Each one of these designations has an impact on eye relief.

Why put so much importance on correct eye relief? 

Setting the correct eye relief maximizes a shooter's magnification field of view. Seeing the fullest FOV downrange without darken circles around the lens dramatically improves accuracy.


What Is Eye Relief?

eye relief on a scope

Eye Relief

A simple explanation of rifle scope eye relief; the shooter is in the firing position, with cheek weld comfortably sitting on the rifle stock. The shooter is looking through the ocular lens of the rifle scope.


From the shooter's eye to a full picture of the target is, you guessed It, eye relief. 


If your eye relief is too short, the shooter sees a dot in the middle of the ocular lens. Too far, and the picture is fuzzy.

Industry-standard for rifle scope eye relief is 3 ½ inches.

Until recently, the standard was fine on 9x scopes. Downing a trophy buck involved short distances with average to light loads. Only hunters with resources could afford the elite scopes needed to hunt big-game.


The market today is filled with affordable precision optic scopes with magnification ranges above 20X. Scopes from Nikon and Vortex feature a line of high-end rifle scopes with magnification ranges of 24X, 35X, and 27X.


 Add to that, Magnum cartridges by Weatherby and Winchester and hunters are faced with a recoil beast.


Every rifle scope model in the world has a designated optimum eye relief. Shooters need to know this number and what game they hunt. Or they risk the dreaded Scope Eye. Many hunters believe the standard distance should be moved out to 4 ½ inches due to the rapid development of Bigger is Better attitude.

Concepts That Affect Eye Relief?

1.

Field of View

FOV refers to the area, in feet, seen by the shooter at 100 yards. The distance a shooter sees in the scope is measured from right to left. As the magnification of the scope is increased, FOV goes down. Conversely, as magnification is dialed down, FOV goes up.

2.

Magnification

When a shooter views their target through a rifle scope, magnification changes the perceived distance as compared to what is visible by the naked eye. More magnification does not ensure a higher level of accuracy.


However, the greater the magnification, the further away your target can be viewed with accuracy.


Typically, the higher the magnification a rifle scope provides, the shorter the eye relief. This correlation can be a significant issue if the hunter is using high-recoil magnum shells.


With lighter loads and shorter distances, eye relief will not be much of an issue.

3.

Magnification

When a shooter views their target through a rifle scope, magnification changes the perceived distance as compared to what is visible by the naked eye.


More magnification does not ensure a higher level of accuracy. However, the greater the magnification, the further away your target can be viewed with accuracy.


Typically, the higher the magnification a rifle scope provides, the shorter the eye relief. This correlation can be a significant issue if the hunter is using high-recoil magnum shells.


With lighter loads and shorter distances, eye relief will not be much of an issue.

What is Exit Pupil

When you have a properly balanced and level rifle scope, looking through the ocular lens should produce a clear, round, and full picture of your target image.


The scope projects your target image through the ocular lens toward your eye in a cone shape. The further out the image travels, the larger it becomes until it reaches optimal size.


The distance is eye relief, and the image is the exit pupil. Larger exit pupils are more forgiving and provides more light.


exit pupil diagram

The pupil of the human eye is between 2mm and 7mm in size. To calculate the size of an exit pupil image, take the diameter of the objective lens and divide it by the magnification. In a perfect world, the exit pupil should match the size of your eye pupil.


Here is the tradeoff: If the exit pupil is much larger than your eye pupil, light is lost and provides less picture. In low-light conditions or higher magnification settings, a better quality scope with a larger objective lens would be a better value.


Quality scopes with multi-coated lenses and higher percentages of light transmission will outperform lesser quality scopes with the same objective lens. Better quality allows the scope to be mounted further away and return the same quality optics.

5 Optical Elements In A Long Eye Relief Rifle Scope


1

Magnification

is critically important when purchasing a rifle scope. Remember, your eyes are closer to the scope with higher magnification levels.


If you plan on hunting big-game with long-range precision targeting, magnification becomes even more critical to your success. However, big-game, magnum cartridges, and powerful rifles equal substantial recoil.


Most experts agree; eye relief on powerful setups should be at least 5 inches at the lowest magnification setting.

2

The Reticle

is critically important for accuracy and a successful hunt. The aiming point should give adequate information, adjustment, and holdover positioning for a good idea of the bullet's trajectory.

3

Optics

are an essential asset in the quality of a rifle scope. Lenses should be anti-glare and multi-coated. They should transmit as much light as possible to give the shooter a clear, crisp picture of the target. Optics should provide the ultimate contrast in low-light situations.

4

Diopter Adjustements

Diopter Adjustment is used only for focusing the reticle. Never use the Diopter to focus on the target.Diopter adjustments are similar to windage, adjust once, then leave the control alone. If your scope is equipped with Diopter, look through the scope at a plain colored background, around 20 feet away.


Adjust the Diopter until the reticle is clear and perfectly in focus.

4

Parallax

is the most complicated and confusing adjustment to new scopes. A parallax error means the reticle and target are not on the same focal plane. In other words, the target looks like it is in 3D.


Scopes equipped with parallax turrets control the issue quickly. 


For most hunting environments, parallax issues are negligible.

A Quality Rifle Scope With Long Eye Relief

UTG 2-7X44 30mm Long Eye Relief Scout Scope. The UTG is an affordable scope with excellent characteristics. Any hunter going for light to medium weight game should consider this scope. The UTG has a good magnification range for a variety of hunting conditions.

The UTG features nearly 11 inches of eye relief.

Another useful feature is the option to customize the reticle. UTG gives you the option of choosing from 36 colors or customize to surrounding conditions.


One of the best options for the UTG is the Zero locking and Zero resetting features. Put your Zero in place at whatever yardage is comfortable and lock it in place. You now have your standard Eye Relief.


If the Zero goes out of place hit a button, and it is reset.

How Far Back Should I Mount My Scope?

The first rule of thumb, when fitting a scope, "never alter the shooter's position" Moving the firing position forward or back to accommodate the scope, draws them out of their comfort zone.


This unnatural positioning leads to loss of accuracy and missed shots.


Precision Fire from YouTube gives the Viewer an excellent presentation on adjusting for eye relief BEFORE installing your rifle scope. The video stresses, take the time to establish your optimal position. If you take the time it makes all the difference in the world to how your accuracy and efficiency improves.


Mounting a rifle scope for proper eye relief is a straightforward process. Always leave room for play and adjustment later.

  • Point your rifle at a light-colored background and lock the firearm down. Install the mounting base or bottom half of the scope rings—torque any hex nuts to 65 inch-pounds.

    If you are installing a quick-detach (QD) base, adjust the tensioner to eliminate any play between mount and receiver.

    Check for ring alignment. Do not wait until you are setting up for zero to find the scope is not aligned correctly. Place the scope in the rings and leave some play for adjustment. 
  • Now is the time for the shooter to assume their most likely firing position. Make certain the shooter is in the exact position with arms and shoulders properly aligned with the objective lens.

    Use different firing positions to simulate other shooting conditions. Find a happy medium.
  • Start moving the scope closer to the eye until a dark ring appears. Move the scope out slightly from the eye until the effect goes away, and there is a full FOV coming from the ocular lens.

    Continue moving the scope away from the shooter's eye until the dark circle effect is completely gone. 

    Move and reverse until the shooters has the brightest and clearest field of view from several positions. This final position is the proper eye relief for your scope.
  • Leave an inch or so of leeway on either side of the eye relief point for different shooting positions and magnification settings. 

    Place a small bubble level on several areas of the scope and rifle to make sure the set up is at absolute level. 

    If the scope or rifle is out of alignment in the slightest, this throws off the entire process.
  • Carefully tighten the ring tops without pushing the scope out of alignment. Head to the range and Zero that shiny new scope.

Conclusion


muzzleloader scope zeroing

Remember the good ole days when hunting was throwing the rifle in the back of the truck and heading for the hills. Little to no consideration was given to the technologies of the day before the hunt. Quite frankly, there weren't any!


Modern hunting is so much more fun and engaging, now that technology has taken a firm hold on our equipment. The great component of all the breakthroughs in precision optics, rifle materials, and long-range ballistics is the opportunity to be extremely accurate. No more aiming for the right side of the animal. Accuracy has allowed elite shooters to target precise areas, no more than two inches at several hundred yards.


No longer do elite marksman shoot from the hip. Trajectories, bullet drop, and ballistic charts are available for every cartridge and rifle made. Eye relief and exit pupil are now accounted for and studied by inexperienced to the elite. The more eye relief and exit pupil have been analyzed, experts have agreed; these small intangibles are fundamental ingredients to precision accuracy.


Every scope and firearm builder in the world have begun adjusting to the new normal in hunting, precision accuracy, and the elite shooter. Trends are followed for long-range hunting and competitions.


Ballistics, like the 300 Weatherby Magnum cartridge, has been available for over 50 years. Only recently are the firearms been around to take advantage of the firepower.


All the technology boils down the image the shooter sees from their ocular lens mounted on the rifle. Once the ramifications of eye relief are understood, elite shooters will keep those 3 to 4 critical inches in the back of their minds forever.

For other rifle and scope types check:

Related Posts

How to Choose a Rifle Scope

How to Zero a Scope and Rifle

How does a rifle scope work?

George Grey


Being an avid outdoorsman since I can remember, my passion for survival, hunting and the outdoors has grown every year. I love being out in the country and living off it whenever time allows.

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