· 6 min
Resolution is worthless without the right angle
A badly placed 4K camera produces unusable footage, while a decent camera in the right spot lets you identify a face. The question is not how many megapixels, but what you need to recognise, and at what distance.
For reliable facial identification you need roughly 250 pixels per metre across the area concerned. That calculation, not the spec sheet, determines how many cameras you need and where. One camera at the entrance, framed at face height, beats three wide-angle cameras mounted high.
Night vision: infrared or lighting
Most break-ins happen at night, so night performance is not a detail. Infrared gives a black and white image, enough to detect movement but often too limited to tell the colour of clothing or a vehicle.
If colour matters, you need either a low-light camera or supplementary lighting in the area. In Dakar, well-placed outdoor lighting often improves usable footage more than changing the camera.
Retention time, the forgotten criterion
A theft is rarely discovered the same day. If your recorder only keeps three days, you will often find the problem after the footage is gone. This is the most common disappointment with entry-level systems.
Retention depends on camera count, resolution and drive size. Seven days is a minimum, fifteen to thirty is a reasonable target for a shop or warehouse.
IP or analogue, a matter of context
Analogue still makes sense where coaxial cabling exists: it avoids redoing everything and costs less. IP becomes necessary as soon as you want high definition, plate reading or gradual expansion.
The real trap is a poorly managed mix of both, which multiplies points of failure. A homogeneous installation, even a modest one, beats a heterogeneous assembly.
And the power supply
A system that dies with the mains fails exactly when risk is highest. A UPS on the recorder and network is a modest investment for what it guarantees.