Parallax Adjustment for Scopes: What It Is & Why It’s a Must

You’ve got your rifle scope ready, great! Now that you’ve got the basics covered, you need to make sure that you know the tips and tricks on how to get the clearest shot in the field.

Listen carefully, okay? We’re letting you in on the secret of your rifle scope’s parallax: what is it? Why do you need it? How do you adjust it?

This is your one-stop scope parallax adjustment guide.

What Is Rifle Scope Parallax?

Parallax refers to the apparent movement of objects when viewed from different positions. It’s an optical illusion that “seems” to happen when you move your head in favor of a differently angled view.

No, the object is not moving — it’s your sight that’s simply changing when you move your head!

In other words, the position of your reticle on your target and the relationship of your eye or what you see.

Tell us if this sounds familiar:

You’re hunting deer.

Your reticle is aligned exactly with your target.

And after shifting your eye position, parallax kicks in (you don’t notice this immediately), and upon firing, you miss the bullseye!

You may THINK you’re looking at the center, but really, it’s actually a little more to your left or right.

In rifle scopes, this occurs in any of these two situations:

1. When the target image is not in focus, or
2. When the focal plane of the object in the rifle scope is not on the same optical plane as the reticle

It’s also more common when aiming over long distances. And that’s why you should take note of the focal plane.

Scopes that do not have adjustable parallax have a fixed parallax.

But often confused with the focus, you might also forget that your rifle scopes usually have their own separate parallax adjustment knobs.

So really, how are they different?

Parallax vs. Focus

Parallax does not affect the focus of both the reticle and the image.

What parallax does is it only accounts for the possible shift in your perception. Not at all the ability of the rifle scope to give you a clear view.

Simply, parallax refers to the position of the reticle on your target in relation to your eye.

It’s quite literally what you’re seeing through your rifle scope.

How Do You Know When You’re Experiencing Parallax?

When looking through the scope, try to adjust your gaze slightly. Change your angle and position.

If the reticle appears to be floating or unknowingly moving from left to right, then you’ve got yourself a parallax.

This means your parallax is not properly compensated for at that range.

Notice that reticle movement is apparent in reference to the target image because the focal planes are not aligned. Rather, they are at an angle. Your reticle shouldn’t be moving at all if adjusted properly.

No matter how you position your head, no matter where you hold your gaze, the reticle should stay in place.

More importantly, your reticle and target should be on the same focal plane.

Do I Have to Adjust the Parallax?

Yes – you most definitely should. Why?

• Simple answer: To get a more accurate shot.
• The ergonomic and efficient answer: To account for human error.

You’re obviously out in the field to shoot. And for you to do that, you need to ensure accuracy and precision. That’s what adjusting the focus and eliminating parallax is for.

But also, an often overlooked consideration is that parallax needs to be corrected because we’re all human!

Parallax adjustment may seem as simple as aligning the reticle to the target. It’s actually that contextually simple.

And yet, it’s only possible maybe if you have the ideal cheek weld and you have the superpower to always have your eyes come back to your scopes the exact way at any given time.

But this doesn’t happen in real life. And this is why we make room for all these adjustments, whether it’s with the cheek weld or on other things.

Anatomy of the Rifle Scope

In order for you to completely understand parallax adjustment and HOW you can get your parallax corrected, let’s quickly brush up on your anatomy first.

Of course, you have the following primary components:

• Objective Lens
• Focus Lens
• Magnification Lens
• Ocular Lens
• Reticle

For parallax adjustments, we pay close attention to the roles of the lenses.

Objective Lens

Sometimes referred to as the bell, you adjust this when using an adjustable objective (AO).

From a given distance, shifting the AO would easily shift your reticle to align itself with the image along the same focal plane.

One added benefit is the depth focus of an AO. Especially for a far distanced target in a wide enough range, this would account for less head movements.

In the end, a parallax-free shot is easy to achieve for a scope with an adjustable objective. This is because such scopes do not have an additional turret to pay attention to when doing a parallax-free shot.

Focus Lens

You adjust this when correcting a side focus.

Shifting the side focus to a higher degree will shift the assembly towards the objectives. Shifting it to a lower distance thus shifts the focus lens closer to the ocular assembly.

The side focus is convenient because of its visible marks. You’ll especially find it beneficial for wind reading under certain weather conditions.

The presence of a side focus turret may also help to control the illumination in a reticle. That’s why side focus is usually highlighted when doing an adjustment.

The side focus is used for more deliberate shots while the AO is for hunting. Both of them, however, are great for long-range shots. The side focus just barely edges AO out because of its markings.

How Do You Adjust the Parallax?

First, have your knob or ring set at the maximum value past infinity.

With prior knowledge about your scope, also make sure your rifle is zeroed. This is so that all scope adjustments will be optimized to account for scope parallax issues.

Follow these step by step:

1. Stabilize your rifle. First, aim at your target while resting on sandbags or machine rests.
2. Put as much distance between you and the target within your shooting range.
3. Set your magnification setting to the maximum distance.
4. Use your scope to set up a good sight picture. A good sight picture is key for good results.
5. Move your head and shift your gaze while accounting for eye relief. Look for any signs of parallax.
6. Adjust the focal planes until there is no movement of the reticle when you shift your gaze. Do the focal plane adjustment using the turret, objective ring, or AO.
7. You may mark all necessary points to ensure the non-movement of your knobs.

These steps are important in order to also account for any inconsistencies in yardage markings. Wrong yardage markings or focal plane adjustments will affect the results.

You may try this scenario after scenario by adjusting your shooting range, your shooting position, or your cheek weld position. This way, you’re aware of any difference each parallax adjustment feature makes!

Point at your target image, verify your magnification, and do every single thing possible to consider. This is quite possibly the perfect way to fix your scope’s parallax setting.

Sounds tedious but easy, right?

Device measurements are accurate to a fault. They may fully serve as mere guides but remember: it’s what your eye perceives that’s more important.

Is It Necessary to Adjust While in the Field?

Yes. Do so while varying your distance per target.

Muscle memory while in the field is important. It allows you to instinctively set your rifle and scope according to the appropriate parallax dial.

To illustrate parallax dial, imagine this situation:

• For a target at the 10-yard mark, you manually try to point towards it, adjust your side focus, your AO, and your focus plane. You do everything by the book.
• Once you’ve adjusted side focus, then you carefully check for the presence of parallax with the parallax adjustment dials.
• You do the necessary changes until you see that your optimal and parallax-free image is at a dial measure of 12 yards.
• You take note of every ring adjustment, each magnification, and every single thing that you have done to achieve such image.
• Thus, when you realize that your dial parallax setting is set at 12 yards, you’ll know that a parallax adjustment under the situation in the future should follow this protocol.
• For a target with a mark 10 yards away from you, your dial and parallax setting should be at the 12-yard mark.

This means that each side focus parallax adjustment to align your reticle to the target on the same focal plane should become a muscle reflex for you. Each mark should become familiar to you, whether it’s the side focus or not.

Under this context, parallax adjustment becomes a skill more than a simple following of procedure for the parallax dial.

Why Do I Need to Know About Parallax Error?

Correcting parallax understanding allows us to value parallax error. By acknowledging the existence and causes of parallax error, we are able to take shots with certainty and confidence.

The gun may be something that’s important, but overlooking simple factors such as parallax error may be more detrimental to you than it is a nuisance.

Then again, despite doing all that you can to achieve parallax correction, parallax error will always exist to an extent. The human eye has a natural eye aberration that makes parallax error an always recurring issue.

We can, however, minimize parallax error.

Who Is Parallax Adjustment For?

The majority, if not all hunters, should know how to adjust their own rifles. Regardless of whether or not you’re using power scopes, knowledge about this would always be useful in the field.

But if you belong to any group from this list, then you’re most likely to be part of the good majority of those who need to have theirs adjusted and eliminate parallax:

• Pellet shooters and air gun shooters
• Long-range target shooters 
• Varmint hunters
• Big game hunters 

Benefits of Parallax Adjustment

With a general notion for a clearer image and target view, a handful of benefits can be gained when you eliminate parallax:

• More accurate and precise shots
• The image easily appearing at the same focal plane as the reticle
• Easier to improve one-shot kill rate
• Easier to shoot at varying distances because of flexible parallax setting
• More versatile gun for all hunting conditions and distances
• Reduces the demand for accessories such as cheek weld, sandbags, tripods, etc.

Disadvantages of Parallax Adjustment

It goes without saying that there are also disadvantages that come with adjusting your gun’s parallax:

• Makes things complicated when you sight in rifle scopes
• Heavier and harder to carry scope
• More costly than getting better optics, a fixed objective, or cheek weld

Yet despite these disadvantages, you have to assess your situation.

Once out in the field, time is of the essence. Do you think you’d have the time to manually adjust your gaze? To adjust your head and your eye? To adjust your range and distance?

Honestly, the tradeoffs are simply outweighed by the benefits. What is the extra weight and cost for a guaranteed parallax-free shot?

Especially when hunting in a group, knowledge about the basics really wouldn’t hurt anyone.

The fact of the matter is: If you have the choice to make your hunting easier and more accurate, TAKE IT.

Final Thoughts

With shooting, one of the first things you should consider is the state of your rifle and scope. After that, you have to make sure that all details and accessories are accounted for.

With shooting, a single movement can disrupt your whole game.

Attention to detail is important.

Knowing what parallax is and how it affects your performance is important in order for you to get a good game. Because sometimes, it’s is all about perspective.

REMEMBER: Do NOT be afraid to make parallax adjustments. Do NOT be afraid to make them until it becomes natural, reflexive, and instinctive to you.

Good luck, and we hope you get that parallax-free shot!

CHANGELOG:

August 31, 2022 - Added 1 new article link
May 5, 2022 - Made minor updates to content, updated article title
September 16, 2021 - Reviewed and updated article links