Shooting Accuracy: What is a Parallax Adjustment on a Scope?
Although the parallax is one of the concerns of hunters and shooters when buying optics, this irrational fear usually stems from unenlightened or ill-advised users.
As first, parallax as a phenomenon is present and visible only in high-powered optics above 10X magnification and at longer ranges, say over 250 yards.
Since the shooting at ranges of 250 yards for many hunters is infrequent occasion considering clean kill and hunting ethics, there remains a small portion of highly specialized sharpshooters from long range shooting disciplines, military as well as civilians.
The majority of parallax adjustment scopes come with magnification over 8x or so and adjusting scope's parallax setting for every distance may sound slow and cumbersome.
While the military operators are passing through the months of extended training, enthusiasts from shooting sports disciplines and extreme range hunters have at their disposal few gun courses and almighty internet.
A riflescope parallax or parallax error is a known optical illusion where the focal plane of the target in the scope is offset from the reticle, i.e. when the object and reticle are on different planes within the riflescope.
When the distance increases, the adverse parallax effect is more pronounced and it must be corrected.
Whereas the adjustable parallax scopes are mandatory for precision long-range target shooters and varmint hunters who are looking to take down their query from various extreme distances, many centerfire riflescopes for big game hunters come without parallax adjustment.
For most of their style of shooting and common hunting distances between 70 to 250 yards, parallax may not have presented too much of a problem. All riflescopes for centerfire rifles without parallaxcorrection ability are going to be set by the manufacturer at 100 or 150 yards or meters.
Some shooters confuse the parallax error with focus what is incorrect, as the parallax adjustment changes neither the focus of the reticle nor the focus of the image; its purpose is to put the reticle on the same focal plane as the target.
You can most natural notice parallax issues as an apparent movement of the reticle when you move your head and eyes in a different position.
If the crosshair changes position on the target when you shift your head or eye, your parallax is not correctly compensated for at that range.
Utilizing an adjustable ring on the objective​​​​ lens (AO) or more commonly an adjustable knob on the side of the scope you must compensate for parallax. Properly adjusted, the reticle seems locked in place, becomes clearer and centered right where it should.
The parallax adjustment dial is marked with various distances ranging from 50 yards to infinity, but you should ignore thesefactory yardage markings because they are more for references.
Whether your high powe​​r scope is equipped with an adjustment ring located on the objective bell or side-mount turret you should set the parallax to be ready to shoot or hunt.
Obviously, the parallax compensation can complicate the use of a riflescope and it is a little time consuming to use. On the other side, you should only have to do this scope calibration once at various distances and that procedure can be arranged in several steps.
Aim your rifle downrange at your target set at the maximum distance possible (1,000 yards or less).
Obtain a sight picture through the scope and look for parallax. It looks a little silly while moving your head around behind the rifle scope but when the reticle appears to move around the object you are aiming at, it is time to properly compensate your parallax error.
Small note: Keep adjusting - slowly then checking. With a parallax dial set on the stop past "infinity", you should try experimenting until the image is a sharp and optical illusion is gone. If you turn more than you needed to, i.e. overshoot, you cannot go back to adjust but you to have to start the process again.
Parallax is one of the most misunderstood terms in shooting community causing many talented riflemen will never nail a sub-MOA group.
Sometimes eliminating parallax can cause slight image blurriness but a lot of shooters describe a third turret/knob as a side focus and dial it until the object is as clear as possible. However, this is a common mistake, as the image does not have to be perfectly clear, but only as far as enough to recognize the center of your target.