This guide works through the decisions in the order they matter: what you need to see, how the system is wired, which cameras and recorder to choose, how much storage you need, and the UK rules to follow. It is brand-neutral. Where we have a deeper guide on one topic, we link to it.
The short version: decide what each camera must show (an overview, or a recognisable face or number plate). Choose IP for new installations, or HD over coax to reuse existing coax cable. Size the recorder and hard drive for your number of cameras and the days of footage you need to keep. Our
CCTV range covers each step, from single cameras to complete kits.
1. Start with what you need to see
Megapixels alone don't tell you whether a face will be recognisable. What matters is how many pixels land on the target, called pixel density, and that depends on resolution, lens and distance together. The international CCTV standard IEC 62676-4 gives these working figures:
| Purpose | Pixels per metre at the target | What it means in practice |
|---|
| Detect | 25 px/m | You can tell a person or vehicle is there |
| Observe | 62.5 px/m | You can see what someone is doing and what they are wearing |
| Recognise | 125 px/m | You can recognise someone you already know |
| Identify | 250 px/m | You can identify a stranger beyond reasonable doubt |
A wide lens covers more area at lower pixel density. A narrower lens, or a varifocal lens zoomed in, puts more pixels on a doorway or gate. Many sites use one wide camera for an overview plus a narrower one at each entry point.
2. IP or HD over coax?
| IP (network) CCTV | HD over coax (HD-TVI / analogue HD) |
|---|
| Cable | Cat5e or Cat6 network cable, up to 100 m per run | Coax (for example RG59), usually with a separate power pair |
| Power | Power over Ethernet (PoE) on the same cable | A separate 12V supply, or power-over-coax on compatible kit |
| Recorder | NVR (network video recorder) | DVR (digital video recorder) |
| Best for | New installations, higher resolutions, smart detection and audio | Upgrading a system that already has coax cable in place |
If you are cabling from scratch, IP is normally the better choice. If good coax is already run to every position, HD over coax lets you upgrade the picture without new cable. Browse IP cameras or NVRs and DVRs.
3. Choose the camera type
Turret, bullet and dome cameras differ in how they mount, how visible they are as a deterrent, and how well they resist tampering. Our comparison turret vs bullet vs dome cameras covers each one. PTZ cameras pan, tilt and zoom to cover large areas, but a PTZ only records where it is pointing at that moment.
Night vision
Most cameras switch to black-and-white infrared (IR) at night. The IR range on the datasheet is the distance it lights; it isn't the distance at which you can identify someone. Colour-at-night cameras (for example Hikvision ColorVu) use a large aperture, and often a soft white light, to keep colour after dark. Read how ColorVu works.
Smart detection
Basic motion detection reacts to any change in the picture: trees, rain, headlights. Cameras and recorders with person and vehicle classification (Hikvision AcuSense, Dahua WizSense and similar) alert you only to people and vehicles, so you get far fewer false alarms.
4. Choose the recorder
- Channels: buy at least one size above your current camera count, so you can add cameras later.
- PoE ports (NVR): a recorder with built-in PoE ports powers the cameras directly. Check the total PoE power budget as well as the number of ports.
- Incoming bandwidth (NVR): the recorder must accept the combined bitrate of all its cameras.
- Drive bays: more bays give more storage, and on larger recorders the option of RAID.
For brand-specific detail, read our Hikvision NVR, Hikvision DVR and Dahua NVR buying guides.
5. Work out your storage
Storage depends on the number of cameras, the bitrate each one records at, hours recorded per day, and the days of footage you keep. H.265 compression typically needs around half the bitrate of H.264 for a similar picture. Use our CCTV storage calculator to size the drive, then choose a surveillance-rated CCTV hard drive, built to record around the clock.
6. Kit or individual parts?
A kit pairs a recorder with matched cameras, which is the simplest route for a typical home or small business. Buying parts separately lets you mix camera types and lenses for each position. See CCTV kits and the HiLook kits buying guide.
7. Follow the UK rules
If a home camera captures images beyond your property boundary, such as a pavement, a road or a neighbour's garden, data protection law applies. You should then be able to justify the coverage, put up signs, keep footage secure and only as long as you need it, and respond to requests for footage. The ICO's guidance on domestic CCTV and GOV.UK's guidance on the use of domestic CCTV set this out. Businesses using CCTV must meet UK GDPR in full. Point cameras at what you need to protect and avoid capturing more than you need.
8. Fitting it
Zenith is a supplier, not an installer. Many of our customers are installers and electricians with trade accounts. If you want a system fitted, use a qualified installer. Bring this guide and your list of camera positions, and you'll get a quote that matches what you need.
Buying from Zenith Security Co.
We have supplied CCTV, alarms and access control to trade and retail customers since 2012, and we are an authorised Hikvision partner. You can order online or visit our Wolverhampton trade counter and showroom. Orders placed before 2:30pm are normally dispatched for delivery within 1–2 working days to England, Scotland and Wales. Browse our full CCTV range or ask us a question before you buy.
