While minimum illumination ratings imply a magical point where image quality goes from good to bad, the reality is that image quality gradually degrades as lighting levels lower. In this report, we share test results showing what this looks like and the rate of decline.

We took three well-known surveillance cameras (from Axis, Arecont and Sony) and put them side by side for a simultaneous shootout from 1 hour before to 1 hour after sunset, recording images and lux ratings at 10 minute intervals. We placed a subject carrying an eye chart at a 30 foot wide FoV. Here's an overview of the scene used:

These tests were performed at progressively lowering light levels of:

• 7,000 lux
• 4,000 lux
• 3,500 lux
• 2,300 lux
• 1,800 lux
• 900 lux
• 330 lux
• 40 lux
• 6 lux
• 3 lux
• 2 lux
• 1.5 lux
• <1 lux

The minimum illumination ratings of each of these cameras also varied, as follows:

• 3.1 MP Arecont: 0.3 lux color/ "Day/Night: 0 Lux, IR sensitive"
• 1080p Sony: 0.4 lux color/0.25 lux black & white @ F1.2
• 720p Axis: 0.4 lux color/0.06 lux black & white @ F1.2

Did these lux ratings hold true? Ha!