Entry Camera WDR Challenges Can Make Identification Difficult.
Entry Camera WDR Challenges – We are having trouble with a camera that with strong backlight is showing people walking through an entrance as silhouettes for a couple of hours each afternoon. Is there something we can do to resolve this issue, or must we install a camera with better WDR performance?
A: It depends. Poor WDR performance isn’t a great quality for an entrance camera and there are compact and full body cameras that do beautiful work in entranceways. We’d be thinking about moving the camera further from the entrance so when set to auto it exposes for the internal environment instead of the external.
You want to use a focal length that gives you good coverage of the entry – typically the camera will be installed close, so you’ll need a wide-ish angle. You want some light – natural light in the day and some external directional light at night so you can see faces with artificial backlight.
Fast shutter speeds are usually the issue with the light at the end of the tunnel effect – a faster shutter means the sensor won’t bloom with 70,000 lux or more in its face. But a fast shutter will render a 500-lux internal environment gloomily at best and dark at worst. Exposing for an internal view won’t come without a price – the external view is going to be overexposed – it will be blown out because excessive light levels are reaching the sensor.
Alternatively, you could also hop into manual mode in camera settings and try to select shutter speed, WDR and brightness that give you the best balance – a slightly darker than ideal internal view and a slight brighter than idea external view without losing one or the other. Obviously, you need to think about what the client needs from the camera before you do this.
Adding a directional lamp to the mix in daylight hours is another worthwhile option. Use a torch to check if this helps – adding a little direct light can do the trick in entranceways. A mirror or a reflective surface – a white-painted wall – could make a big difference.
Something else to consider in entrances is lensing. Many installers will use a low-cost compact camera with a large WDR number and leave WDR at default auto, assuming the problem is solved. Our experience is that harsh entrance environments need the best lenses – they can make a real difference.
It’s fair to say that a marginal plastic lens with an additional front element in the form of an IK10-rated sheet of polymer of unknown quality and clarity, and an aesthetic not an optical bubble, is guaranteed to flare in the presence of direct sunlight.
In the images here you can see the Axis M1125 fitted with an aftermarket Fujinon lens is doing fine work with 72,000 lux of backlight. The other camera is copping flare from direct sunlight very late in the afternoon and it’s not doing too well.
You can learn more about wide dynamic range here or read more SEN news here.
“Entry Camera WDR Challenges Can Make Identification Difficult.”
