AO (Adjustable Objective) and SF (Side Focus) are two types of parallax adjustment systems commonly found in rifle scopes. For airgun shooters—especially those using spring air rifles or PCPs—understanding the difference between AO and SF is a key step when choosing your first scope.
What Is an AO Scope and Why Airgun Shooters Prefer It
AO scopes let you adjust for parallax by rotating a front ring near the objective lens. This adjustment helps align what you see through the scope, making sure the target and the reticle stay in proper focus together, so your aim remains accurate—especially at close distances.
Airgun shooters often choose AO scopes because they provide:
- Precise focusing at short range (e.g., 5–10 yards)
- Simple construction with a lightweight design that suits stationary or benchrest shooting
- Better performance in indoor ranges or tight outdoor spaces
The front-mounted ring may require you to move your support hand to adjust, but for slow, controlled shooting with an air rifle, that tradeoff is minor.
What Is a Side Focus (SF) Scope and Where It Shines
SF scopes use a side dial—usually on the left of the scope body—for adjusting parallax. This makes it easier to fine-tune focus without shifting your position.
SF scopes are more common on centerfire rifles and are typically used in mid-to-long range shooting. Some airgunners do use SF models, but entry-level SF scopes may have limited parallax correction at short distances (below 15 yards), which can be a downside for close-range plinking.
SF is a better fit if your setup involves:
- Longer distances (30 yards and up)
- Frequent adjustments during hunting or field shooting
- A preference for quick and convenient side control
How to Choose Between AO and SF for Airguns
If you’re experimenting with longer ranges or plan to use one scope across multiple rifle types, an SF model could offer more flexibility—but it is less effective when shooting at close range.
While for most airgun beginners, an AO scope is the more practical and precise option. It offers better close-range clarity and is designed with the kind of shooting distances air rifles often work within.
And specially, for spring-piston rifles, break-barrels in particular, scopes face intense recoil, making a simple yet rugged design essential:
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One-piece tube with thick walls: absorbs recoil, reduces damage risk
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Etched glass reticle: shock-resistant for lasting accuracy
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Locking or zero-stop turrets: keeps elevation and windage settings secure
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Built-in AO adjustment: fewer moving parts for reliable focusing
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Fixed or low-variable magnification: stable under high recoil
Here are two great scopes to consider:
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VictOptics SOI 3-9×40 AO (VIOC-05): Offers precise shots from as close as 5 yards, a 5-level red/green illuminated reticle, and a reliable 1-inch tube.
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VictOptics SOI 4-12×40 AO (VIOC-06): Includes all VIOC-05 features, with higher magnification, a 30mm tube, and AO adjustment starting at 10 yards for longer-range use.
Also available in the SOI series of VictOptics: SOI 1.5-5×20 (VIOC-01), SOI 2-7×32 (VIOC-02), SOI 3-9×40 (VIOC-03), SOI 4-12×40 (VIOC-04)—all designed with new shooters in mind. The VictOptics SOI series generally uses a 1-inch tube diameter, ensuring broad compatibility with standard mounting systems.
Choosing Right: AO or SF Scopes
AO and SF each serve a purpose, but when it comes to airguns—especially for new shooters—AO offers the control and clarity needed for close-range precision. Learning how your scope adjusts for parallax will not only improve your aim, but also deepen your understanding of how optics work.
Every shooter starts somewhere. Choosing the right scope helps you start stronger.
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