The complete guide to buying optics for sub-16J airguns — clear, practical, no nonsense

Glossary of Terms

1. FFP (First Focal Plane)Reticle scales with magnification. Holdover marks remain correct at any zoom. Great for field use and varying-range shots.

2. SFP (Second Focal Plane)Reticle size stays co

nstant as you zoom. Good for target work when you dial turrets for range. Usually cheaper than FFP.

3. Magnification (e.g., 4–16×)How many times larger the scope makes the target appear. First number = low mag; second = high mag.

4. Common premium zooms (5–30×, 4–32×)Newer “premium” ranges; give big usable windows for hybrid tasks — more flexible than older narrow ranges.

5. Objective lens (e.g., 44mm)Front lens diameter. Bigger = more light at high mags and better low-light performance; smaller = deeper depth of field, lighter, easier fit.

6. Tube diameter (1", 30mm, 34mm)Central body size of the scope. 30mm is the modern standard; 34mm gives more internal adjustment and is popular with high-end optics / NV setups.

7. Depth of Field (DOF)Area in front of and behind your focus point that stays acceptably sharp. Larger DOF = more forgiving when target or shooter moves.

8. Exit pupilObjective ÷ magnification. Guides brightness to your eye — ideal daytime ~3–5mm. Bigger helps at dusk.

9. ParallaxFocus adjustment for different target distances. Low parallax is important for close-range pest/bell-target work; side-wheel/parallax knob useful for precise mid/long ranges.

10. Eye reliefDistance between the rear lens and your eye while still seeing the whole image. Important for comfort and safety (esp. with recoiling springers).

11. Reticle (wire vs etched)

• Wire: old-school, fragile — avoid on springers.

• Etched: laser-engraved on glass; robust and precise.

12. Illuminated reticle (IR or lit reticle)Reticle center or markings light up for low contrast/dusk. Handy but battery-dependent; etched + illumination can show bleed (normal).

13. Click value / turret units (MOA vs MRAD)How much the point-of-impact moves per click. Make sure your reticle units match turret units (MRAD↔MRAD, MOA↔MOA) to avoid awkward conversions.

14. Zeroing vs dialing

• Zeroing: setting the scope so the pellet hits the aim point at a chosen range.

• Dialing: using turrets to change point-of-aim for different distances (FFP helps holdovers instead).

15. Exit pupil (worth repeating)Helps predict brightness. If exit pupil < ~3mm at your working mag, picture can look dim.

16. IP rating / fogproof / shockproofIndicates weather resistance and ruggedness. Useful if you shoot in wet or rough conditions.

17. Parallax limit / close-focusMinimum range the scope can focus to. Important for close-range bell/indoor shooting — many scopes don't focus closer than ~10–12m.

18. Mount height & clearanceBig objectives may need tall rings and bulky mounts; also watch for fouling cocking handles, magazines or bolt paths.

19. Recoil rating (G-force or calibre-rated)Tells you what recoil the scope can survive. Some brands list calibres (e.g. “springer rated up to .308”), others use confusing “G ratings.” Rough guide:

• Wire reticle scopes: ~100G — fine for PCPs, fragile on springers.

• Etched reticle scopes: ~500G — safe on springers and most powder burners.Higher = tougher, but always check if your scope is explicitly “springer rated.”

20. Sub-16J (UK context)Airguns limited to under 16 joules (unlicensed). Scope choices should reflect likely ranges and the lighter recoil compared to higher-powered guns.

TL;DR Cheat-Sheet (read this first)

• Backyard / pest (0–25m): 3–12× / 4–16×, 30–44mm objective, 30mm tube, deep DOF > light.

• Hybrid (pest + mid-range): 4–16× / 6–24×, 44mm objective, 30mm or 34mm tube.

• Longer ranges / low light / NV clip-ons: 6–24× / 7–35×, 50–56mm objective, 34mm tube.

• Target/score shooting: SFP reticle acceptable; FFP helps for holdovers.

• If in doubt: 44mm objective on a 30mm tube, 4–16× is the safest all-round pick.

• Budget rule: match scope to purpose — don’t force a £100 scope into a job that needs a £400 optic, and don’t buy the fancy glass if you’ll never use the features.

1) Start with the use-case — not the price

Before drooling over numbers, decide what you actually do:

• Pest / rimfire-style shooting at moving targets in fields or hedgerows? You need wide field of view (FOV), quick target acquisition, forgiving DOF.

• Precision target or scoring at known distances? You want higher top magnification, fine adjustment, stable mounts.

• Dusk/dawn/thermal use? Prioritise objective size and tube diameter for light coupling.

If your budget won’t match your intended use, either raise the budget or reduce the scope requirement. Simple.

2) FFP vs SFP — which focal plane?

• FFP (First Focal Plane): reticle scales with magnification. Best when you use holdovers at varying mags (pest/control+range). Good for hybrid and real-world hunting.

• SFP (Second Focal Plane): reticle stays same size. Good for target shooting where you know distances and use turrets to dial in. Cheaper options tend to be SFP.

Rule: for hybrid/pest use pick FFP if available at your budget; for pure target work SFP will do.

FFP vs SFP

3) Magnification — pick sensibly

A simple trick for sub-16J airguns: double the first and last magnification numbers to estimate ideal usable range (in metres).Example: a 4–16× ≈ usable ~8–32m. That makes sense for much sub-16 work.General guidance:

• Short (0–25m): 3–12×, 4–16×

• Mid (25–60m): 4–16×, 6–24×

• Long (60–100m+): 6–24×, 7–35×

Don’t over-magnify — you’ll amplify wobble and make practical shooting harder.

4) Objective lens size — tradeoffs explained (big one!)

Objective = the front lens size (e.g., 44 in 4–16×44).

Bigger objective (50–56mm)

• Pros: brighter at high mags / low light; excellent with night-vision/thermal.

• Cons: heavier, shallower depth of field (DOF), needs taller mounts, sometimes won’t focus close (<12m). Can cause scope-fit headaches on small rifles.

Smaller objective (30–44mm)

• Pros: greater DOF (more forgiving for moving/close targets), lighter, cheaper, easier to fit close to the rifle.

• Cons: less light at high mags / low light.

Exit pupil = objective ÷ magnification. Aim for ~3–5mm in daylight; bigger helps at dusk but only if glass quality is decent.

Rule of thumb:

• Daylight, close/fast work → 30–44mm objective.

• Low light / NV / long range → 50–56mm objective.

5) Tube diameter (1", 30mm, 34mm) — why it matters

• 30mm is now the standard sweet spot for strength, elevation adjustment and adapter availability.

• 34mm / 35mm tubes allow more internal adjustment and can help reach zero at long ranges; also pair well with big objectives and NV/thermal setups.

• 1" (25.4mm) is legacy/budget; avoid if you plan real glass performance.

6) Reticles — wire vs etched and the illumination myth

• Wire reticles (old style): cheap but fragile — NOT recommended for springers (recoil).

• Etched reticles: robust and precise — standard for modern scopes.

• Illuminated reticle: helpful in low contrast or dusk. Downsides: battery dependency and potential bleed (etched IR bleed is normal). Better to have and not need than vice-versa.

Also check reticle type vs turret units — MRAD/MIL reticle should ideally pair with MRAD turrets (same for MOA).

7) Click values, reticle units & math headaches

• Match turret units to reticle units: MRAD↔MRAD, MOA↔MOA. Mixing causes ugly math and never lines up neatly.

• Cheaper scopes sometimes mix units — avoid unless you love conversions.

8) Parallax & DOF — practical importance

• Parallax becomes a real issue at close ranges with big objective/high mag combos.

• For close pest work, get a scope with low parallax (or fixed close parallax).

• For match/long range, a side parallax wheel is valuable.

9) Mounts, rings & clearance — don’t forget the basics

• Big objectives need taller rings and may foul magazines, cocking handles or the bolt. Always check mount height and rail length.

• Use good-quality mounts rated for your tube size. Cheap rings are often the weak link for lost zero.

10) Budget & buying checklist

Before checkout, run through this:

• Purpose matched? (pest/target/hybrid)

• Tube size fits mounts? (30mm / 34mm?)

• Objective fits your rifle (clearance + cheek weld)?

• Parallax spec okay for your distances?

• FFP vs SFP chosen deliberately?

• Reticle units match turret click units?

• Illumination: wanted or unnecessary?

• Mounts included / will you buy rings?

• Return policy & warranty — essential for optics.

11) Quick recommendations (useful examples)

• All-rounder / newbie: 4–16×44, 30mm tube (FFP if budget allows).

• Pest & moving targets: 3–12×40 or 4–16×44 (smaller objective, wide FOV).

• Hybrid + thermal NV: 4-24×56 or 5-30x50 on a 34mm tube.

• Target / match: 6–24×50 (FFP) or SFP target reticle and consistent turret clicks.

12) Final practical tips

• Don’t skimp on mounts — they’re as important as the scope and "included mounts" are not always the best option as you dont get to choose the right ones.

• If you plan NV/thermal later, plan for larger objective & 34mm tube now.

• Try before buying if possible — even an objectively “right” spec can feel wrong in real life.

• Remember exit pupil & eye relief — important for fast acquisition and comfort.

• Keep expectations sensible: a £120 scope can be brilliant for casual pest control; serious match or low-light work will need better glass.

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