Light Flickering - Problem For Surveillance Cameras?

How commonly do you contend with video flickering due to fluorescent light fixture flickering?

The problem often looks similar to this:

Many IP cameras include an exposure setting that inhibits the tight synchronization of camera imager sensor line scanning and the native electrical distribution of AC frequency, ie:

  • 50 Hz: Common to Europe and most of Asia
  • 60 Hz: Common to North America

The actual frequency of the flickering occurs at 100 or 120 Hz, as the cyclic change of AC current affects the output intensity of the lamp and is much faster than the human eye can see. However, given the fast scanning rate of the imager can sometimes be seen with surveillance cameras if the exposure point matches the wrong frequency.

Many cameras include a 'flicker-free' setting that breaks the synchronization of exposures by a tiny bit (a half cycle), and this cures the issue.

However, with that said, how often do you use it? Is flickering a common problem?

I haven't seen flickering be a common problem with most lights. I did run into this problem when shooting something outdoors under high pressure sodium lights last week, however.

Here's the camera set to 60 Hz. You can see some very slow moving bars moving up the image. The lights are obviously not quite 60 Hz.

For the heck of it I set it to 50 Hz to see what happened and it was trippy.

For the record, the frame rate was 30 on both of these. So that wasn't the issue. I could see how it could make slower frame rates look even jerkier, however.

Are those lights on some kind of controller that dims them at night or after a certain time?

That sort of looks to me like the result of a PWM dimming attempt on a high voltage light.

We run into this occasionally but not nearly as much as we used to. I think it is due to my company updating lighting fixtures corporation wide to use more LED or CFL. This has included the parking lots and we have seen a drastic improvement.

Thankfully the areas that do still have the older fixtures AXIS’ settings do the trick to fix the flickering.