CCTV Camera Systems A simple guide
How a CCTV system works, dome vs bullet vs PTZ vs fisheye, analog vs IP, how much storage you need, where to place cameras and how to keep footage safe.
01How a CCTV system works
A CCTV system has four parts: cameras that see, cables that carry the video, a recorder that stores it, and a screen or phone app where you watch it.
The recorder keeps recording until its hard disk is full, then it writes over the oldest footage. That is why storage size decides how many days of video you can go back to.
02Analog (HD) vs IP systems
Both are good. The right one depends on your site and budget.
| Analog HD (DVR) | IP (NVR) | |
|---|---|---|
| Cable | Coaxial cable for video plus a separate power cable | One network cable carries video and power (PoE) |
| Recorder | DVR | NVR |
| Picture | Good HD picture | Higher resolutions and smarter features (detection, analytics) |
| Best for | Small budgets and upgrading old coaxial systems | New installations, offices, societies and larger sites |
03Camera types: dome, bullet, PTZ, fisheye
Compact and discreet. Harder to tamper with or turn away. Good for lobbies, offices, shops and lifts.
Long, visible shape that also deters intruders. Good for gates, parking and building perimeters.
Pans, tilts and zooms to follow activity across a large area. It watches one direction at a time, so use it alongside fixed cameras, not instead of them.
Sees a full 360° from one ceiling point, ideal for halls and stores. Less detail at the edges of the picture.
04Resolution, lens and night vision
- Resolution: 2MP (Full HD) suits most indoor spots. 4MP gives clearer detail for general use. 8MP (4K) helps on wide areas where you need to zoom into recordings. Higher resolution needs more storage.
- Lens: a wide lens (e.g. 2.8 mm) sees more of the room but less detail far away. A narrower lens (6 mm and above) is better for long corridors and gates.
- Night vision: standard infrared cameras show black-and-white at night. Colour night cameras use more sensitive sensors and/or a soft white light to stay in colour.
- Bright backgrounds: a camera facing a sunny gate or glass door can turn faces into dark shadows. WDR (wide dynamic range) helps; good positioning helps more.
To recognise faces, place a camera at each entry point, facing people as they walk in, at a height where it sees faces and not just the tops of heads.
05How much storage do you need?
Each camera sends a stream of data to the recorder. A simple way to estimate it:
Example: 4 cameras recording all the time at 2 Mbps each → about 21.6 GB per camera per day → about 86 GB per day for all four → about 2.6 TB for 30 days. A 4 TB hard disk would cover that with room to spare.
- Real bitrates vary with resolution, compression (H.265 uses less space than H.264) and how busy the scene is.
- Recording only on motion or detection saves a lot of space.
- Use hard disks made for surveillance; they are built to record all day, every day.
06Where to place cameras
- Main gate and every entry and exit
- Lift lobbies and staircases
- Parking and driveways
- Cash counters and billing areas
- Back doors, terraces and loading areas
- The recorder itself: keep it in a locked spot, with a UPS so it keeps recording in a power cut
Avoid pointing cameras into direct sunlight or bright lights, and keep cables covered so they cannot be cut easily.
07Keep your system secure and respectful
- Change the default password on the recorder and every camera, and give each user their own login.
- Keep firmware updated; updates fix security holes.
- For phone viewing, use the manufacturer’s app with a strong password rather than opening ports on your router.
- Respect privacy: do not point cameras into neighbours’ homes or private areas such as washrooms, and put up a visible “CCTV in operation” notice.
08Maintenance: small checks that save footage
- Open playback once a week and check every camera is recording
- Make sure the date and time on the recorder are correct
- Clean camera domes and lenses, especially outdoors
- Watch for hard disk errors on the recorder screen
- Save a copy of any incident clip quickly, before it gets overwritten
An annual maintenance contract (AMC) covers these checks for you. See our AMC plans.
09Common questions
Will my cameras work during a power cut?
Only if the cameras and the recorder are on a UPS or inverter. Without backup power, recording stops until power returns.
Can I watch my cameras on my phone?
Yes. The recorder needs an internet connection at the site, and you install the camera brand’s app on your phone.
How many days of recording will I get?
Until the hard disk is full; then the oldest footage is overwritten. Use the storage estimate above, or ask us to size it for your cameras.
Are Wi-Fi cameras good enough?
They are fine for many homes. For societies, offices and shops, wired cameras are more reliable because they do not depend on Wi-Fi signal.
Need help choosing?
Tell us about your home, society, shop or office. We will suggest what fits, visit the site, and give you a clear quote. See our CCTV installation service.