CCTV, Surveillance & Physical Security
A CCTV system is cameras, cables, a recorder and a way to watch. This guide explains each part in plain words: the camera shapes, IP versus analogue HD, outdoor ratings, night vision, PoE power and recorders, so you can understand a quotation before you pay for one.
What you will learn
Applies to
Tools Required
No tools needed.
Before you start
Important
Step-by-Step Guide
1 / 9 steps
Step 1
The bullet camera
A tube-shaped camera on an arm bracket. The long housing has room for a bigger lens, so bullets suit gates, driveways and long walls.
Expected result: You can recognise a bullet camera and know it is the most visible deterrent.
The lens sits under a clear or tinted cover fixed flat to a ceiling or wall. People cannot easily see where it points.
Expected result: You know why domes suit shops, receptions and corridors.
A ball-shaped camera in a round base, with no cover in front of the lens. It is easy to aim and avoids dome glare at night.
Expected result: You know the turret is the all-rounder for walls, eaves and entrances.
Infrared LEDs around the lens light the scene with light you cannot see. The camera switches to black and white in the dark.
Expected result: You know the IR range on a datasheet is measured in ideal conditions.
An IP camera takes power and sends video over one network cable using PoE. Each copper run can be up to 100 metres.
Expected result: You know why wired PoE cameras are the reliable choice for businesses.
Cameras connect to a PoE switch, the switch to the recorder, and the recorder to the router. The UPS keeps the core running in a power cut.
Expected result: You can follow the path from each camera to your phone.
The NVR writes every camera's video to a surveillance hard drive and overwrites the oldest footage when the drive is full.
Expected result: You know the drive size and the cameras' bitrate decide how many days you keep.
Analogue HD cameras send video over coaxial cable to a DVR. Most need a separate power supply unless they use power over coax.
Expected result: You can tell an analogue HD system from an IP one by its cable and recorder.
Use the manufacturer's app or a VPN with your own account. Do not open router ports to the recorder.
Expected result: You can view live video and playback without exposing the recorder to the internet.
Troubleshooting
Likely cause Bright light behind people and no true WDR, or the camera faces the sun.
Solution Use a camera with true WDR at entrances, re-aim it away from the light, or move it inside the doorway.
Likely cause Infrared reflecting off a dirty dome cover, a nearby wall or eaves.
Solution Clean the cover with a microfibre cloth, check the foam ring around the lens and leave space from nearby surfaces.
Likely cause Lens too wide or camera too far from the subject.
Solution Use a narrower or varifocal lens, or add a camera closer to the doorway or gate.
Likely cause Recorder, switch and router are not on backup power.
Solution Put the recorder, PoE switch and router on a UPS sized for your usual outage.
Likely cause Water in an unsealed cable joint or junction box.
Solution Use the supplied waterproof kit, an IP66 or better junction box and a drip loop.
Likely cause Drive too small for the cameras' bitrate.
Solution Check the bitrate, then use the CCTV storage calculator to size the drive.
In Depth
A CCTV system is cameras, cables, a recorder and a way to watch. This guide explains each part in plain words: the camera shapes, IP versus analogue HD, outdoor ratings, night vision, PoE power and recorders, so you can understand a quotation before you pay for one.
CCTV stands for closed-circuit television: cameras that send video to a limited set of screens and recorders rather than to a public broadcast. A typical system has five parts:
The interactive tutorial above walks through these parts in order and shows how video travels from a camera to your phone.
This is the first big choice, because it decides the cable and the recorder.
Current analogue HD formats reach up to 4K (8 MP) on some models, so analogue is no longer limited to the grainy pictures of old CCTV. IP still offers the wider choice of resolutions, lenses and smart detection, and is easier to extend. For new buildings IP is usually the better choice; analogue HD can be a sensible budget upgrade where good coaxial cable is already in the walls. The full comparison is in IP CCTV vs analogue CCTV.
Plays from YouTube when you press play.
The shape of a camera (its form factor) is separate from the IP or analogue choice. Most shapes come in both.
| Camera type | Typical uses | Advantages | Limitations |
|---|---|---|---|
| Bullet | Gates, driveways, perimeter walls, car parks | Very visible deterrent; easy to aim; room for longer lenses | Easier to knock or spray if within reach; insects and spiders like the sunshade |
| Dome | Indoor ceilings, shop floors, receptions, corridors | Discreet; the cover hides where the lens points; vandal-resistant versions are common | A dirty or scratched cover can reflect infrared and haze the night picture; re-aiming means opening the cover |
| Turret ("eyeball") | Entrances, walls, eaves, indoors or out | Easy to aim; no cover in front of the lens, so no cover glare at night | Lens is exposed, so less tamper-resistant than a vandal dome |
| PTZ (pan-tilt-zoom) | Large yards, hotel grounds, warehouses, school compounds | One camera can be moved and zoomed to follow activity | Costly; when it looks one way it misses the other; needs more power and an operator or presets |
Tip Most properties use a mix: bullets or turrets outside, domes inside, and a PTZ only where someone actually watches live. For the detailed comparison, read bullet vs dome cameras or try the bullet, dome or turret guide.
Plays from YouTube when you press play.
Outdoor cameras face sun, rain, dust and sometimes a thrown stone. Two international ratings, printed on every good datasheet, tell you how well a camera copes.
Warning Ratings apply to the camera only. A badly sealed cable joint or junction box can still let water in. Ask how every connection will be protected, especially near the sea.
Plays from YouTube when you press play.
Resolution is measured in megapixels (MP). 2 MP is 1920 × 1080 (1080p), 4 MP is usually 2560 × 1440, and 8 MP is 3840 × 2160 (4K). More pixels show more detail, but they also need more storage and network bandwidth. Our guide to how much CCTV storage you need shows the effect.
The lens decides what those pixels are spread over. A short focal length such as 2.8 mm gives a wide view of a room but shows faces small; a longer lens such as 6 mm or 8 mm sees less width but more detail further away. Varifocal lenses can be adjusted during installation, and motorised versions can be adjusted from the recorder. A wide 8 MP camera can show less detail on a face at the gate than a narrow 4 MP one.
Night vision comes in two main types:
WDR (wide dynamic range) helps when a scene has bright and dark areas at once, such as a doorway with sun behind the people walking in. Without it, faces become dark silhouettes. Look for "true WDR" with a dB figure on the datasheet for entrance cameras.
How much storage you need depends on the number of cameras, their bitrate and how many days you keep. Try the CCTV storage calculator.
Plays from YouTube when you press play.
| Property | What usually matters | Typical starting point |
|---|---|---|
| Home | Gate, doors, parking, simple app | 2 to 4 IP turrets or bullets outdoors, small NVR |
| Shop | Till, entrance faces, stock areas | Domes over till and aisles; WDR camera at the door |
| Office | Reception, server room, entrances | Domes indoors; turrets at doors; access control can complement CCTV |
| Hotel / guesthouse | Gates, parking, lobby, corridors, beach or pool access | Mix of turrets and domes, perhaps a PTZ for the grounds; strict privacy zones |
| School | Gates, corridors, play areas | Vandal-resistant (IK10) domes; clear policy on who views footage |
| Warehouse | Loading bays, perimeter, high racking | Bullets with longer lenses outside; high-mounted cameras inside; PTZ for yards |
These are starting points; a site survey decides the final design. For a step-by-step business plan, read how to choose a CCTV system for a business in Zanzibar.
When you know what you want to protect, Extrion can survey the site, design the camera positions, cabling and backup power, and install and hand over the system with your own admin password. See our CCTV installation service, request a quote or contact us.
This guide is general information. Procedures, product features and firmware change, so check your own equipment's documentation before you start.
FAQs
Not always. IP is usually the better choice for new installations because of its wider choice of cameras and simpler PoE cabling. Analogue HD can be a sensible budget upgrade where good coaxial cable is already installed.
An NVR records IP cameras that send already-compressed video over a network. A DVR records analogue cameras over coaxial cable and does the compression itself. Hybrid recorders accept both.
No. Megapixels only help if the lens puts enough of them on the subject, and more pixels mean more storage. A well-chosen 4 MP camera with the right lens often beats a badly placed 8 MP one.
For a position exposed to rain, look for IP66 or better on the datasheet. IP67 covers temporary immersion, which is a different test, so many outdoor cameras state both.
For one or two cameras close to the router, perhaps. For continuous, reliable recording across a business, wired PoE cameras are the safer choice.
Only if the cameras, recorder, switch and router are on a UPS or other backup power. With PoE, backing up the switch also backs up the cameras it powers.
Long enough to notice and investigate an incident, often one week to one month. This is common practice, not a legal figure. The storage guide shows what that means in disk space.
Our engineers survey the site, choose the right cameras and recorder, install them neatly and set up safe remote viewing.
Ask for clarification, tell us a problem this did not solve, or suggest a topic. An engineer reads every message, and we use them to improve the Knowledge Center.
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