Flashlight Camera Testing

I was curious if IPVM has done any testing on flashlights and washing out cameras. An audio forum discussion a while back got me into 4Sevens flashlights. I wanted a nice flashlight that accepted AA batteries (so I could use Eneloop batteries) and something with dual modes. I wound up with a 270 lumen flashlight which was fairly bright and I have a headband that I use to wear the flashlight. This was before the brighter headlamps were available. This Christmas I had asked for another small 4Sevens flashlight that was rechargeable via USB, had dual modes and was brighter. I now have the 800 lumen flashlight. It has a really long-throw spot beam. When I got home a couple days ago at night, I decided to see the effect of aiming it at the camera as I walked from my van to my house holding the flashlight near my head aimed at my cameras. Once the flashlight was on from about 10-15' away with Dahua 2.8mm 3MP cameras I looked like a floating white light from my van until I turned the light off to unlock my door.

Is there anything one can do to combat a relatively inexpensive bright flashlight from defeating a camera of any details. I realize that multiple vantage points come into play but I could really attach three more to my head and it would seem that no one would be able to come close to identifying me. I haven't tried this during the day but I would assume a much different outcome given the brightness of daylight.

There is always the obvious point that instead of a flashlight, just wear a mask and you won't need a light to draw attention to yourself.

...a light to draw attention to yourself.

Discreet criminals know how to BLIR - Blind with IR...

Kyle, we have a test on car headlights which creates a similiar phenomenon / problem.

Dealing with high lux beams of light is inherently difficult. The options are mainly:

  • Add your own light source next to the camera (i.e., brighten up the area) to counteract the light coming from the flashlight.
  • Shorten the exposure of the camera to minimize the amount of light that the camera lets in from the flashlight. This is logistically difficult to do given the flashlight can occur at random times.

In your headlight test you don't mention auto-iris specifically as a way to control exposure, I assume this is because the time for auto-iris typically to react to headlights is too long and too unpredictable to be of use.

But in this case when there is a sustained illumination lasting several seconds or more, automatically stopping down the lens might help quite a bit, yes/no?

Also, mirrored domes could help; they give back some of what they get, and would certainly be irritating to an approaching flasher if nothing else...

Problem with auto-iris and shutter speed is that even though both of them control the exposure (respectively width and time), usually cameras will not 'crank them down' in the dark when a headlight or flashlight is exposed because most of the rest of the scene will still be dark.

Btw, I recall their being some special camera mode that a few cameras offered / claimed to deal directly with this. I can't recall the marketing term they used though.