How to choose security cameras without overbuying
Resolution is the specification everyone compares and the one that matters least. What to look at instead.
Camera marketing is a resolution arms race. 4K, 8K, more megapixels every year. Resolution is genuinely the least useful number on the spec sheet, and buying on it is the most common way people end up with expensive footage they cannot use.
Ask what each camera is for
Surveillance cameras do one of three jobs, and the job determines everything else:
- Identify — you need to recognise a face or read a plate. Requires tight framing on a known choke point, like a doorway.
- Recognise — you need to tell whether it is someone you know. Wider framing acceptable.
- Observe — you need to know that something happened and roughly where. Wide coverage, detail not required.
A camera set to observe a whole parking lot cannot identify a face, no matter its resolution — the pixels are spread across too much scene. This is why a single 4K camera covering everything performs worse than two well-placed cameras at lower resolution.
Low light is where cameras actually differ
Most incidents happen in poor light, and this is where cheap cameras collapse. Two things matter far more than resolution: sensor size and lens aperture. A larger sensor with a wider aperture gathers more light, and no amount of processing recovers detail that was never captured.
Infrared illumination is nearly universal but has limits worth knowing. It produces monochrome images, so clothing colour is lost. It has a stated range that assumes a reflective subject. And it reflects hard off glass, which is why a camera pointed through a window at night usually shows a bright wash and nothing else.
Lens choice, briefly
- Wide angle covers more but shrinks everything in frame. Good for observing a space, poor for identifying anyone in it.
- Narrow angle covers less with far more detail. Right for doorways, tills, and gates.
- Varifocal lets the angle be adjusted at commissioning. Worth the small premium — the ideal angle is rarely obvious until the camera is physically mounted.
The specification nobody checks
Storage retention. A system that keeps seven days is useless if you discover a problem after a long weekend plus a few days. Thirty days is a common sensible minimum; some insurers and regulations require more.
Retention is driven by camera count, resolution, frame rate, and compression. This is the real reason to be careful about resolution: doubling it roughly doubles storage cost across every camera, permanently. Spending that budget on better placement and better low-light performance produces more usable evidence than spending it on pixels.