Infrared or colour: what to look for in night vision

A camera that looks excellent in a showroom at two in the afternoon can be close to useless at eleven at night. Night performance is where cameras actually differ, and it is the hardest bit to judge from a spec sheet.

Infrared: everything in grey

Most cameras have a ring of infrared LEDs around the lens. In the dark the camera drops its infrared filter and lights the scene with light your eye cannot see. It works, it is cheap and it is reliable.

What you get is a monochrome picture. You can see a person, a vehicle and what they did. You cannot say what colour the car was or what colour coat they had on, and those are two of the first things you will be asked.

Colour at night: a bigger sensor and a small light

The alternative uses a more sensitive sensor with a wider aperture, plus a low-level warm white light that comes on when it needs to. The picture stays in colour, so descriptions survive.

The trade-off is that it needs a little ambient light to work with, and it costs more per camera. On a property with a porch light or any street lighting nearby, it is usually worth it on at least the identification camera.

The specification that actually matters

• Infrared range in metres, and be realistic: a 30 m rating means 30 m to see something, not 30 m to identify somebody.
• Aperture, written as f/1.6 or similar. Lower is better in the dark.
• Sensor size. A bigger sensor at the same resolution collects more light per pixel, which is why more megapixels can actually make night performance worse.
• Whether the light is switchable, so you are not lighting a bedroom window all night.

The practical answer

Mix them. Infrared is fine on the wide cameras that are giving you context. Put the colour camera where you need to describe somebody, which is normally the door approach. That is what we do on most jobs, and it costs less than putting the expensive camera everywhere.