You buy a camera rated at 110°, mount it above the garage, open the app — and the number plate on the car at the gate is a grey smudge. The spec was honest. The expectation wasn’t.
Security camera field of view is the single most misunderstood number in CCTV, because it only tells you how wide the camera looks, never how much you’ll actually be able to see. Those are two different questions, and mixing them up is why so many New Zealand homes and small businesses end up with four cameras and three blind spots.
This guide fixes that. You’ll get the actual geometry (with a coverage table you can use), the pixel-density rule that decides whether footage is evidence or just movement, a millimetre-to-degrees lens chart, and realistic camera counts for a typical NZ property — plus the mistakes that quietly shrink your coverage after installation.
What “field of view” actually means
Field of view (FOV) is the angular width of the scene a camera can capture, measured in degrees from the lens. A 90° camera sees a quarter of a circle. A 180° camera sees a flat half-circle wall of view.
That angle is fixed by two things: the focal length of the lens (in millimetres) and the size of the image sensor behind it. Short focal length plus large sensor equals a wide security camera viewing angle. Long focal length equals a narrow, magnified one. Resolution has nothing to do with it — an 8MP camera and a 2MP camera with the same lens and sensor see exactly the same angle.
Horizontal, vertical and diagonal — and why brands quote the biggest one
Every camera has three field-of-view figures, and they are not interchangeable:
- Horizontal FOV — side-to-side coverage. This is the number that matters for driveways, fence lines, corridors and shop floors.
- Vertical FOV — top-to-bottom. Usually a little over half the horizontal figure on a 16:9 sensor. This is the number that decides whether you capture faces or the tops of heads.
- Diagonal FOV — corner to corner, and always the largest of the three.
Consumer brands love quoting the diagonal because it’s the most flattering. If a listing says “150° field of view” with no qualifier, assume diagonal and mentally knock 20–30% off for the horizontal. When you’re comparing two cameras, compare horizontal to horizontal or you’re comparing nothing at all.
How much area can one security camera cover? The simple maths
Coverage isn’t a rectangle — it’s a wedge that keeps widening as it goes. The width of that wedge at any distance is straightforward:
Coverage width = 2 × distance × tan(FOV ÷ 2)
You don’t need to run it yourself. Here’s the horizontal coverage width, in metres, at common security camera viewing angles:
| Horizontal FOV | At 3 m | At 5 m | At 10 m | At 15 m | At 20 m |
|---|---|---|---|---|---|
| 40° (telephoto) | 2.2 m | 3.6 m | 7.3 m | 10.9 m | 14.6 m |
| 60° | 3.5 m | 5.8 m | 11.5 m | 17.3 m | 23.1 m |
| 90° | 6.0 m | 10.0 m | 20.0 m | 30.0 m | 40.0 m |
| 105° | 7.8 m | 13.0 m | 26.1 m | 39.1 m | 52.1 m |
| 120° | 10.4 m | 17.3 m | 34.6 m | 52.0 m | 69.3 m |
| 130° (wide angle) | 12.9 m | 21.4 m | 42.9 m | 64.3 m | 85.8 m |
Read that table once and the appeal of wide-angle cameras is obvious. A 120° camera covers nearly six times the width of a 40° lens at the same distance. A single 110° camera at the corner of a house can span an entire 15-metre frontage from about 10 metres out.
But notice what the table doesn’t say: nothing about detail. Which brings us to the part the box never mentions.
Wide view, useless detail: the trade-off that decides everything
Your camera has a fixed number of pixels across the frame. Widen the field of view and you spread those same pixels across more metres of scene. Every extra degree of coverage costs you detail on everything in it.
The security industry measures this properly as pixel density — pixels per metre of scene (px/m) — and grades it against the international CCTV standard IEC 62676-4, usually shortened to DORI:
| Requirement | Pixel density | What you can actually do |
|---|---|---|
| Detect | 25 px/m | Tell that a person-shaped thing is present |
| Observe | 63 px/m | Track movement, see clothing colour and general behaviour |
| Recognise | 125 px/m | Identify someone you already know |
| Identify | 250 px/m | Identify a stranger to an evidential standard |
Those thresholds are published in Axis Communications’ pixel density white paper based on IEC 62676-4, which also notes the practical rule of thumb: roughly 40 pixels across the width of a face for identification.
Now combine that with field of view. A 4MP camera has 2,560 horizontal pixels. Set it to a 105° horizontal FOV and here’s the honest security camera viewing range:
| Task | 4MP @ 105° FOV | 4K/8MP @ 90° FOV |
|---|---|---|
| Identify a stranger | up to ~3.9 m | up to ~7.7 m |
| Recognise someone known | up to ~7.9 m | up to ~15.4 m |
| Observe behaviour | up to ~15.6 m | up to ~30.5 m |
| Detect presence | up to ~39 m | up to ~77 m |
That’s the number people are really asking for when they ask how far a camera can see. Manufacturer “night vision range” and detection figures — eufy’s guide to how far a security camera can see puts typical viewing range at roughly 9–30 m — describe detection, the loosest tier on the list. Court-usable identification happens far closer to the lens than most buyers assume.
The practical takeaway: every camera position needs a job. Overview cameras can be wide. Any camera guarding an entry point, till, gate or letterbox needs its field of view tightened until that target sits inside the identification zone. One wide camera doing both jobs does neither well.
Security camera lens angle: millimetres to degrees
Fixed-lens cameras state a focal length. Here’s roughly what each one gives you on the 1/2.8-inch sensors common in 4MP and 4K CCTV cameras, and where each one earns its place on a New Zealand property:
| Focal length | Typical horizontal FOV | Best used for |
|---|---|---|
| 2.8 mm | ~100–110° | Front door, garage interior, open-plan rooms, small courtyards |
| 3.6 mm | ~80–90° | Driveways, decks, side paths, retail floor overview |
| 4 mm | ~75–87° | Standard all-rounder — front walkway, carport, entry approach |
| 6 mm | ~50–60° | Long driveways, gates, boundary lines, car parks |
| 8 mm | ~38–42° | Rural gateways, yard entries, loading bays |
| 12 mm+ | ~25–28° | Number-plate capture, long approaches, distant sheds |
Two caveats worth knowing, because they explain most of the confusion in product listings.
First, the same focal length gives different angles on different cameras. A 2.8 mm lens on a larger sensor sees wider than the same lens on a smaller one. That’s why one brand’s 2.8 mm is 95° and another’s is 110°. Always trust the stated degrees over the millimetres.
Second, wide-angle lenses bend the picture. Very wide security camera lens designs use deliberate barrel distortion to squeeze in more scene, which is why quoted angles often exceed what the raw geometry predicts. The edges of a 110° frame are always softer and more stretched than the centre — so never put your most important target at the edge of the frame.
Fixed, varifocal, PTZ or panoramic?
- Fixed lens — one angle, locked in at manufacture. Cheapest, most reliable, and completely unforgiving if you guess the angle wrong.
- Varifocal (motorised zoom) — adjustable, commonly 2.8–12 mm, so you can dial the field of view in after mounting. Worth the premium anywhere you can’t predict the framing: long driveways, awkward corners, gates. ANNKE’s motorised varifocal models in the ANNKE NZ camera range cover this bracket.
- PTZ — a narrow, high-detail view you can steer across a very wide area. Excellent for monitored sites, risky as your only camera: it’s blind to everything it isn’t currently pointed at.
- Panoramic / fisheye — 180° or 360° in one housing, usually with software dewarping to flatten the curve.
Are 180-degree security cameras worth it?
Sometimes, and the maths shows exactly when.
A 180° camera doesn’t cover an infinitely wide strip — geometrically, the wedge flattens into a straight line, so the useful measure becomes area, not width. A 180° camera at 8 metres of usable range covers about 100 m² of ground. Excellent for a wide frontage where you’d otherwise need two cameras pointed in opposite directions, or a T-junction corridor.
The cost is pixel density. Spreading a sensor across 180° means every metre of scene gets very few pixels, so a 180-degree security camera is an overview tool. Use one to answer “what happened and where did they go”, then let a narrower camera answer “who was it”.
The better panoramic units get around this with multiple sensors stitched together — two or three lenses each covering its own slice, so each one keeps a workable pixel density. If a wide-angle security camera in NZ conditions is on your shortlist, check whether it’s one sensor stretched wide or several sensors combined. It’s the difference between a compromise and a genuine upgrade.
Planning real coverage: how many cameras do you need?
Camera count comes out of your property’s geometry, not a package deal. Work through it in this order.
1. List your assets and approaches. Front door, back door, garage, driveway entrance, side gate, ranch slider, letterbox. Every property has three or four routes an intruder will actually use.
2. Assign a job to each position. Overview or identification. Then pick the field of view to match, using the tables above.
3. Mount at 2.5–3 metres, tilted down 10–15°. This is the single highest-impact decision you’ll make. Too high and your vertical FOV catches the tops of heads and hats — useless for identification. Sub-3 metres keeps faces in frame and stays out of easy reach.
4. Overlap adjacent cameras by 10–15%. Butt two 100° wedges up against each other with no margin and the seam between them becomes a blind spot the moment one camera is knocked by wind or a ladder.
5. Watch the sun. In New Zealand, the low winter sun sits in the north. A camera facing directly into it will silhouette everyone who walks in front of it. Aim across the light or specify strong WDR and good low-light performance — night-vision and colour night cameras exist precisely because most incidents happen in poor light.
Typical outcomes on real NZ properties:
- Standard suburban three-bedroom on a full or half site: 4 cameras. One 2.8 mm at the front door (identification), one 3.6–4 mm covering the driveway and garage, one 4 mm on the back door and ranch slider, one 6 mm down the side path or across the rear boundary.
- Larger or corner site with a long drive: 6 cameras, adding a varifocal at the gate for vehicles and one filling the second street frontage.
- Small retail or workshop: 4–6 cameras. A wide overview of the floor, one tightly framed on the till or counter at identification density, one on each external door, one on the stockroom or yard.
Five mistakes that shrink your field of view after installation
Mounting too high. Eaves and second-storey walls feel like the safe choice. They cost you faces and give you scalps. Come down to 2.5–3 metres.
Ignoring vertical FOV. People plan the horizontal sweep and forget the camera also has a top and bottom edge. Steep downtilt on a wide lens can put the far half of a driveway completely out of frame.
Letting the lens choose the position. A 2.8 mm camera 12 metres from a gate will never identify anyone. Either move it closer or fit a longer lens — no resolution upgrade rescues bad geometry.
Forgetting infrared washout. At night, IR bounces off nearby walls, glass and spiderwebs, blowing out the near part of the frame and blinding the rest. Keep the first metre of view clear of surfaces and clean the housing seasonally.
Aiming across the boundary. Wide angles overshoot property lines easily. The Office of the Privacy Commissioner’s guidance on CCTV at home is explicit: don’t point a camera directly at a neighbour’s property, doors or windows, and put up signage telling people cameras are in use. Use privacy masking to block off what you don’t need, and be aware that businesses recording identifiable people carry obligations under the Privacy Act 2020.
Test your coverage before you commit
Two low-tech checks save most of the regret:
The walk test. Before drilling, hold a phone camera at the intended mounting height and angle and record a clip while someone walks every approach route. Phone rear cameras sit around 70–80° horizontal, so what you see is narrower than a 2.8 mm CCTV lens will capture — a conservative preview. If your subject leaves the frame or looks too small, the position is wrong.
The face test. After installation, stand at the exact spot you care about most — the door, the till, the gate — and check the recorded footage, not the live view. If you can’t confidently identify a stranger’s face there, that camera is an observation camera. Add or retask one that can.
FAQs
What is a good field of view for a security camera? For general outdoor coverage, 90–110° horizontal is the sweet spot: broad enough for a driveway or frontage, tight enough to keep useful detail. Go wider (120–180°) only for overview positions, and narrower (40–60°) where you need to identify people or vehicles beyond about 10 metres.
How much area can one security camera cover? A 110° camera spans roughly 8.6 m across at 3 m, 28.6 m at 10 m, and 57 m at 20 m. Reliable identification, though, is limited to a few metres — around 4 m for a 4MP camera at 105°, or about 7.7 m for a 4K camera at 90°.
Is a 2.8 mm or 4 mm lens better? 2.8 mm (roughly 100–110°) suits close, wide scenes like a front door, garage or small courtyard. 4 mm (roughly 75–87°) trades some width for more detail at distance, making it the better all-rounder for driveways and entry approaches.
How far can a security camera see at night? Infrared night vision on most residential cameras reaches 20–30 m for detection, but recognition happens much closer because IR illumination falls off sharply with distance. Colour night vision cameras with larger apertures hold detail considerably better in low light.
Does higher resolution increase the field of view? No. Field of view is set by lens focal length and sensor size. Higher resolution keeps more detail within the same field of view — which is why a 4K camera can be aimed wider than a 1080p one and still deliver usable identification.
Are 180-degree security cameras any good? For overview coverage of a wide frontage or an open floor, yes — one camera can replace two. But pixel density at 180° is low, so pair it with a narrower camera on your key entry point rather than relying on it alone.
Can my security camera legally film the footpath or my neighbour’s place? Incidental capture of a public footpath is generally accepted, and the Privacy Commissioner notes that images visible from the street aren’t usually considered highly offensive. Deliberately aiming at a neighbour’s doors, windows or private areas is not acceptable — mask those zones out and signpost your cameras.
The bottom line
Security camera field of view tells you how wide a camera looks. Pixel density tells you whether that footage will be worth anything. Plan with both and the whole exercise gets simpler: wide angles for the overview, tighter angles where identification actually matters, mounted at 2.5–3 metres with a small overlap between neighbouring views.
Get those three decisions right and four well-chosen cameras will outperform eight badly aimed ones — at lower cost, with less cabling and no blind spots at the seams.
Ready to match a lens angle to your property? Browse the ANNKE NZ range of PoE security cameras — including motorised varifocal models you can fine-tune after mounting — or shop the full ANNKE New Zealand catalogue for complete kits with NVR and local support.
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