Phill Price offers expert advice on scope basics, to improve your accuracy
Hard to understand yet vital to success, parallax adjustment must be understood
If there’s one thing that marks out a true airgun scope from a model designed for firearm use, it’s parallax adjustment that comes down to 10 yards or metres. Often, firearm scopes are adjusted to be parallax free at 100 yards, and if they have an adjustment feature, it will only go as low as 50 yards. Ironically, parallax error gets greater as the range reduces, which might not be a problem for the Scandinavian hunter looking at the side of a moose, but is a huge problem for the airgun hunter looking at a feral pigeon’s head at eight yards.
To understand why parallax error is such a problem, we need to understand what it is. The objective (front) lens of our scopes need to focus the light reflecting off our quarry exactly on the reticle (cross hairs). This can only ever be correct at one distance. If the quarry moves closer or further away, the focus becomes incorrect and the opportunity for an aiming error comes into play, but if we refocus to the new distance, the problem is eliminated.
If the image is focused in front or behind the reticle, it becomes possible to look through the scope at an angle and perceive that you’re aiming correctly, when in fact, you are not. You’ll miss your target yet not be unable to understand why, which is enough to drive you mad! This is why a proper airgun scope needs parallax adjustment and please don’t listen to anybody who tells you differently.
Parallax adjusters come in two flavours. The traditional one is a collar that’s around the outside of the objective ( front) bell of the scope’s body. This was a simple, light and cheap method of correcting parallax. In more recent times, the side wheel parallax adjuster has become by far the most popular. It makes for a much more modern and slick- looking optic, plus the control dial is easier to reach. On the down side, this system adds another lens, complexity and cost to any scope, so there’s a price to pay.
Whichever type you choose, it’s vital to maximising accuracy that you estimate the range to your target and reset your adjuster as close to the optimum point that you’re able. This will greatly reduce the number of random misses that you cannot explain, and put more quarry in the bag.
“it becomes possible to look through the scope at an angle and perceive that you’re aiming correctly, when in fact, you are not”
Objective mounted (left) or side wheel, parallax adjustment is vital to the airgunner