X
Get all access to the world's best video surveillance information.
Logo
680-70-2015-free-banner

Don't Trust Lux Ratings

by John Honovich, IPVM posted on Jan 09, 2013 About John Contact John

Do not trust lux ratings. Do not use lux ratings to specify cameras. Period.

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 manfacturer specifications:

lux ratings examples

For instance, a camera with 0.02 lux is supposedly 'better' in low light than a camera with 0.05 lux. (Background - See our Lux / Lux Meter Tutorial).

[New Test Results show the reality of low light image quality.]

However, they are so riddled with fundamental problems that lux ratings must be abandoned.

Widespread Misconception

In regular IPVM assessments, we find easily half of surveillance professionals believe and use lux ratings as a viable metric for assessing low light performance.

More importantly, lux ratings are overwhelmingly used in RFPs to require specific low light performance. Cameras that do not meet the RFPs lux ratings specification are rejected.

The Fundamental Problems

Here are the fundamental problems:

  • Unrealistic numbers
  • No standard process
  • No revelation of what image looks like
  • Failure to disclose camera settings
  • Gradual image quality decline

Unrealistic Numbers

Most manufacturers have lux ratings that are incredibly unrealistic, with ratings of .001 lux or lower common. However, that is incredibly dark. Almost any camera truly in such conditions in the real world would capture nothing or be so dark and noisy as to be practically useless.

No Standard Process

Each manufacturer measures on their own, by themselves and with whatever 'standards' that they like. As such, it is impossible to compare the results of two manufacturers without more knowledge or testing of one's own.

No Revelation of What Images Look Like

No manufacturer ever releases images of what their cameras look like at their claimed lux ratings. Almost certainly, the images would be terrible.

Failure to Disclose Camera Settings

Many manufacturers use tricky settings such as using super slow shutters and fostering tricks like 'sens up'. Often they will obscure this in their specification, resulting in seemingly eye popping low lux ratings like 0.000001 lux.

Gradual Image Quality Degradation

The image quality of all cameras gradually declines as light levels fall below 50 lux, with falling signal to noise ratios, and increasing gain control levels. There is no magical point where quality turns from good to bad.

Consultant's Fault

The lion's share of the blame goes to consultants who regularly specify cameras based on minimum illumination specifications though they rarely if ever test to verify that the ratings are accurate.

Manufacturer's Trapped

This creates an ugly system where even the most ethical and responsible manufacturers are trapped. The first manufacturer to 'tell the truth' about their low light performance will be disqualified from many large projects. Because of this, no one can afford to do so.

Worse, it rewards the most unscrupulous vendors who realize that they are rarely, if ever, called on their specs.

What To Do?

The best way is to test cameras head to head in the same conditions with the same fundamental settings (especially shutter speed). For example, see our MP low light shootout. Take your finalists and place them for an evening in your desired deployment location. I can almost guarantee that the results will not match what the lux ratings suggest.

Short of that, a few specifications do deliver:

  • F Stop: While small differences in F numbers (1.2 vs 1.4) have limited practical impact, going from F1.2 vs 2.4 typically has a major impact on low light quality.
  • True Day/Night: Cameras with mechanical cut filters consistently deliver notable increases in low light performance.
  • Adding IR: If a scene is quite dark and you want to ensure maximum illumination, consider adding IR either through integrated IR or add-on illuminators.

There is no magic number. Unfortunately, lux ratings are voodoo, more smoke and mirrors than reality. Let's move past them and focus on better metrics for reliably specifying high quality low light performance.






Most Recent Industry Reports

ioimage HD Analytic Camera Tested on Jan 29, 2015
Four years after acquiring ioimage, DVTel has released new HD analytic cameras, with the promise of higher probability of detection and lower false alarm rates.   Now, the question ...

Testing Integrated IR Cameras In Snow on Jan 28, 2015
'Snowmaggedon 2015' gave us an oppportunity to test cameras in heavy snow conditions. Integrated IR has gained in popularity, improving low light images even in low cost cameras. However,&nbs...

2015 Video Surveillance Guide on Jan 27, 2015
The 250+ page, 2015 Video Surveillance Industry Guide, covering the key events and the future of the video surveillance market, is now available. Table of Contents How To Get It There are 3 ...

How to Hack an ADT Alarm System on Jan 26, 2015
This report explains the key steps in hacking an alarm system, like ADT, as was presented in a Defcon 22 presentation. The risk of such a hack has become major news as a class action lawsuit was f...

Simplicam Facial Recognition Tested on Jan 23, 2015
Facial recognition, available for $150? That's the offer from a startup, Simplicam, who has not only cloned Dropcam setup and user interface but has added in facial detection and recognition....

Bosch 4K Tested on Jan 21, 2015
4K promises more pixels but does it undermine WDR and low light performance? We tested the Axis 4K camera and there were certainly issues. Now, we tested the Bosch 4K camera, the Dinion IP Ultra ...

Largest New Video Surveillance Projects on Jan 19, 2015
140 video surveillance professionals, including integrators and manufacturers, shared the largest video surveillance projects that they have seen in the past year. Key Patterns The survey results...

IP Networking Course - Last Day Save $50 on Jan 18, 2015
[Today is the last day to save $50 - register now.] This is the first networking course designed specifically for video surveillance professionals. IPVM is launching an IP Networking for Video Su...

Bosch Buys $190 Million Integrator on Jan 16, 2015
The big deals continue. This time, Bosch has bought a US integrator, Climatec, that did ~$190 million in 2014 revenue.

Testing $50 Mini NVR on Jan 14, 2015
As an NVR, this performed very really badly. But, as a member suggested to us, could a $50 mini NVR be used as an IP / HD spot monitor? Adding a spot monitor or public view display in an IP sur...