How Much Light Does A CCTV Camera Need?
When you’re planning a surveillance system that’s expected to perform at night it’s important to answer the question – how much light does a CCTV camera need?
You should also try to remember the inverse square law which decrees that light spreads out the further it gets from its source – you need to work angle the required depth of field and go from there. The inverse square law means the intensity of light is inversely proportional to the square of the distance it has travelled from the source. Essentially this means that if light has an intensity of 1 when measured 1 metre away from its source then at 2 metres the intensity will be ¼ and at 4 metres it’ll be 1/16th of its strength at 1 metre.
If you’re looking to get greater intensity out of a single luminary, you need to think about cramping your field of view and using a lamp with a curved lens in order to create a collimated light beam. Using a concave lens, it’s possible to ensure that about 50 per cent of the light produced by a luminary will reach the target area at an appropriate distance for the relevant lamp strength – this is excellent performance.
Having said all this, the latest IP cameras incorporating white and IR LED light are also worth considering, especially if there is no existing ambient light and a camera must be installed to cover the angle of view. Some of the better cameras have outstanding IR and white light performance – that includes affordable models, too.
There are further considerations – whether the target is moving, how fast it’s moving, the overall reflectance of the scene, the reflectance range of targets and more. Camera characteristics play a part – especially sensor size. Camera settings may help but only if there’s a quality image stream for them to work on.
The best way to work out lighting needs is in the field, where you’ll find the camera engine interferes with your lighting plans in curious ways, including elevated noise, slower shutter speeds, odd colour casts and more.
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