Know the equipment before you choose

A lens sits inside a half-sphere cover fixed to the ceiling or wall. The cover hides where the lens points and protects it from tampering. Infrared LEDs let it record in darkness, and one network cable (PoE) carries both video and power.

A cylindrical body on a wall bracket, aimed in one fixed direction. Its visible shape deters intruders, the front hood shields the lens from sun and dust, and it reaches further than a dome.

An internal motor turns the camera a full 360° (pan), tilts it (tilt) and magnifies with an optical lens (zoom) without losing detail. Operators steer it from the control room or a phone, or set patrol tours and motion tracking.

One ultra-wide lens in the middle of the ceiling sees the whole room as a circular image. Software flattens it into several normal views, so one camera can replace several.

It reads heat given off by objects instead of light and turns it into an image. It picks out people and vehicles in total darkness, dust and smoke, and some models alert on rising temperature for early fire detection.

An infrared-lit camera with a fast shutter captures the plate even on a moving car. Character-recognition software turns it into text and checks it against the allowed list, opening the gate automatically and logging entry and exit times.

A camera with an on-board AI processor finds faces in the frame, converts each face into a digital template, and compares it with an enrolled database to grant entry or alert on an unauthorised person.

The reader shines a gentle, safe near-infrared light on the eye and photographs the iris pattern, which is unique to each person and stays stable. It turns the pattern into a digital code and matches it in about a second, contact-free, and works through most glasses.

A door-side unit checks identity by fingerprint, face, card or PIN, then releases the electric lock and logs the time, linking to the attendance system.

An NVR receives IP camera streams over the network and stores them with space-saving H.265 compression; a DVR records analogue cameras on coaxial cable, upgrading older systems without re-cabling. Both give live view and playback, locally or remotely.

Drives built for non-stop writing from many cameras at once, unlike ordinary PC drives. Their capacity sets how many days of footage the system keeps.

A PoE switch powers the cameras and carries their data on the same network cable, and a UPS keeps the system running through power cuts so recording never stops.