As we spoke about in our blog “the difference between accuracy and precision”, the most important thing about rifle shooting at long range is consistency and predictability. One of the variables that can affect your rifle’s consistency is rifle scope parallax.
So what is scope parallax?
Scope parallax is an inconsistency in the view that you see when you look down the rifle scope. It causes the cross hair to move across the target when you shift your eye position. This means the reticule will not accurately reflect where your rifle is pointing. This is only a problem in higher magnification scopes and much more noticeable the higher the magnification.
Since the amount of parallax within the scope is variable depending on the distance of the target to the shooter, it’s important to ensure that you’re always compensating and adjusting for parallax.
What causes scope parallax?
When you look through a rifle scope, the magnified image that you see in front of you is where all of the light rays entering the optic are focussed. You are essentially seeing a projected image. Parallax issues occur when the projected image is too far away (front or behind) from the cross hairs inside the optic.
Imagine a reticule sticker on a window, and putting a picture at the end of the garden, the reticule would change where it’s pointed depending on where you stand in the room. This is an exaggerated case of parallax.
To remove parallax issues, you want to get the projected image (the picture) as close as possible to the scope’s reticule, so that there’s no room for movement. Put a reticule sticker on the window and then stick the picture on the other side of the glass. No matter where you stand in the room, the reticule is pointed at the target correctly.
This is how you solve parallax issues.
Many modern scopes and optics will have the ability to change the focal point of the image inside the scope and it’s often marked by distance. Adjustment rings may be on the front objective lens, as a middle turret adjustment, or in the rear eye piece, depending on the quality and type of scope that you are using.
How to adjust for parallax:
Place your rifle into a shooting stand or securely anchor it to a shooting table. You want to remove any shakes and wobbles when adjusting, any variances in shooting position – whilst they won’t ruin your ability to adjust – will make it harder to perfect.
Adjust the parallax adjustment ring to be as close as possible to the range you’re shooting out to. Rather than adjusting all the way up to the range, have a quick guess at the distance from target and dial it in from there. Bear in mind that these markings are not always accurate.
Aim down sight and adjust your eye position slowly.
Pay attention to the reticule’s position on the target. If you’re seeing the reticule move as you move your eye, you’re experiencing parallax issues.
If you move your head to the left slightly, pay attention to how your reticule moves. If the reticule moves to the left on the target, your image is too far in front of the reticule and you need to INCREASE the distance of the adjustment. If the reticule moves to the right on the target as you move your head left, you need to DECREASE the distance adjustment.