If you have fitted a riflescope to your sniper rifle or DMR, you may have noticed that the reticle seems to move across the target when you shift your head slightly. That is parallax. On an airsoft site we shoot at short distances, and that is exactly where parallax can give you a blurred image and a point of aim that is not quite where you think it is. Here we explain what parallax is, when it matters in airsoft and what you can do about it.
What is parallax?
A riflescope forms an image of the target inside the scope, and the reticle sits in a fixed plane inside it. Parallax occurs when the target image and the reticle do not lie in the same plane. The reticle then appears to move across the target if your eye is not exactly centred behind the eyepiece – even though the gun is perfectly still.
When the parallax is set to the distance you are shooting at, the target is sharp and the reticle stays put on the target, wherever your eye is. If it is set to a very different distance, the image is less sharp and your point of aim depends on how you hold your head.
Why does it matter in airsoft?
Most riflescopes leave the factory with parallax fixed at around 100 metres (or 100 yards, approx. 91 m). That setting is designed for shooting with a rifle. In airsoft we typically shoot at 20–60 metres, depending on the site and your role. In other words, there is a big gap between the fixed setting and the distances you actually use the scope at.
- At low magnification (1–4x) the parallax error is so small that it rarely matters. This is one of the reasons why short scopes and short dots work well for DMRs and all-round play.
- At high magnification (8x and up) the error becomes obvious, and the image turns blurred at short range. This is where adjustable parallax gives you a sharper image and a more stable point of aim.
- Red dot sights are often marketed as parallax-free. Most of them are only approximately so, but without magnification and at airsoft distances it makes very little difference in practice.
Adjustable parallax: AO and side focus
Riflescopes that let you set the parallax yourself come in two versions:
- AO (Adjustable Objective): You turn a ring out at the objective lens. Inexpensive and simple, but you have to reach forward to adjust it.
- Side focus (SF): The adjustment sits as a turret on the side of the scope, so you can set it without breaking your shooting position. One example is the Victoptics AGN 4-16x44, where the focus can be set from 12 yards (approx. 11 metres) to infinity – a good match for airsoft distances.
Many side focus scopes can be fitted with a larger side wheel, which makes fine adjustment easier. The Vector Optics Sidewheel fits several Vector Optics scopes – check that it fits your particular scope.
How to set the parallax
- Focus the eyepiece on the reticle. Look at a bright, plain surface and turn the eyepiece dioptre until the reticle is sharp straight away. You only need to do this once.
- Rest the gun steadily, for example on a backpack or a bipod.
- Turn the magnification up – the error is easiest to see at high zoom.
- Turn the AO ring or side focus until the target is sharp.
- Do the head test: Move your head slightly up, down and to the side behind the eyepiece. If the reticle stays put on the target, you are set. If it moves, adjust a little more.
On the field, it is a good idea to set the parallax to the distance you shoot at most often – for example 40 metres – and only adjust it when you move to a position at a markedly different distance.
Do you have a scope with fixed parallax?
Then two things help more than anything else:
- Consistent cheek weld: Place your cheek in the same spot on the stock every time, so your eye sits centred behind the eyepiece. This keeps the parallax error to a minimum. A stock with an adjustable comb or a cheek pad can help.
- Lower magnification: At short range you rarely need full zoom. Lower magnification gives a wider field of view, a brighter image and less parallax error.
A scope such as the Victoptics SOI 3-9x40 has its parallax fixed at 100 yards, but works well on an airsoft sniper rifle as long as you keep your eye centred and do not wind the magnification all the way up at short range.
Parallax is not the same as hop-up
If your shots go astray even though the scope is set up correctly, the cause often lies in the gun and the BBs: hop-up, inner barrel or BB weight. The scope can only show you where you are aiming – the BB's trajectory is determined by the gun. Read more in our hop-up guide and in how to upgrade your airsoft sniper rifle. Use heavy, consistent BBs such as Hank Tactical BIO 0.40 g in your sniper rifle to keep the trajectory stable, and always zero the scope with the BBs you play with.
If you are choosing a sight, also read red dot sight or riflescope for airsoft?, or browse our full range of riflescopes.
Our recommendations
- Victoptics AGN 4-16x44: Side focus from approx. 11 metres, a 30 mm tube and Picatinny scope rings for airsoft in the box. An obvious choice for a sniper rifle where you want a sharp image at typical airsoft distances.
- Victoptics SOI 3-9x40: An affordable, lightweight scope with fixed parallax. Good for DMRs and sniper rifles when you work with a consistent cheek weld and moderate magnification.
- Vector Optics Sidewheel: A large side wheel for side focus scopes that makes it easier to adjust the parallax quickly during a game. Check that it fits your scope.
