What is a Lux Rating?

Cameras with low-lux ratings are the norm in the market. You may have seen security camera manufacturers using specifications 0.75 lux@F1.5 to show how outstanding their camera can reproduce image in low light condition. Claims of 2 lux, 1 lux, 0.75 lux and even 0 lux are not uncommon. What do these ratings really mean? What is a lux?

In a nutshell, the lux is the metric unit for measuring the amount of light that falls on an object, and is the European equivalent of the British foot-candle (or lumen). Specifically, 1 lux equals the amount of light that falls on a one-square-meter surface that is one meter away from a single candle. 10 lux equals the amount of light produced by 10 candles one meter away.

Lux ratings are widely, and unfortunately, used to define low light performance, with the lower the lux rating, the stronger low light performance. Here's what this commonly looks like on manufacturer specifications: For instance, a camera with 0.02 lux is supposedly 'better' in low light than a camera with 0.05 lux.