1 CCTV SYSTEMS LIGHTING AND ILLUMINATION

2 CCTV SYSTEMS A video camera requires light to work properly, without sufficient light the video camera can’t receive enough information to form an image. During a 24 hour period, light conditions outside can change, the lighting can go from extremely bright to extremely dark.

3 CCTV SYSTEMS Indoor lighting conditions can change as lights are turned off and on, depending on the time of day and other factors.

4 CCTV SYSTEMS Indoor light can be affected by light entering through windows, and light levels can change significantly by opening or closing a door. Outdoor lighting conditions can also change during the switch from natural to artificial light sources. Indoor light can be affected by light entering through windows, and light levels can change significantly by opening or closing a door. Outdoor lighting conditions can also change during the switch from natural to artificial light sources.

5 CCTV SYSTEMS A camera receives light through its lens, the lens iris is used to adjust the aperture of the lens to allow more or less light to reach the imaging element. Factors such as environmental and atmospheric conditions can affect the amount of light received by the lens. High levels of dust or liquid spray in the area can not only affect the amount of light, but can severely limit the field of view. A camera receives light through its lens, the lens iris is used to adjust the aperture of the lens to allow more or less light to reach the imaging element. Factors such as environmental and atmospheric conditions can affect the amount of light received by the lens. High levels of dust or liquid spray in the area can not only affect the amount of light, but can severely limit the field of view.

6 CCTV SYSTEMS Atmospheric conditions such as heat or humidity can cause lighting levels to fluctuate, distorting incoming images. In many cases the lens iris can compensate for varying degrees of light. Atmospheric conditions such as heat or humidity can cause lighting levels to fluctuate, distorting incoming images. In many cases the lens iris can compensate for varying degrees of light. LENS IRIS APERTURE

7 CCTV SYSTEMS The point here is that the camera used in certain spaces either has to compensate for the changes in lighting conditions or be aimed away from direct light sources. Cameras installed outdoors are outfitted with a sun shield that acts like the lid on a baseball cap to shade the lens from direct sunlight. The point here is that the camera used in certain spaces either has to compensate for the changes in lighting conditions or be aimed away from direct light sources. Cameras installed outdoors are outfitted with a sun shield that acts like the lid on a baseball cap to shade the lens from direct sunlight.

8 CCTV SYSTEMS Natural light is light received from the sun. The human eye is sensitive to solar radiation with wavelengths between 400 to 750 nanometers (nm), the human eye is most sensitive to light at 555 nm. What color do you think is in the 555 nm wavelength? Natural light is light received from the sun. The human eye is sensitive to solar radiation with wavelengths between 400 to 750 nanometers (nm), the human eye is most sensitive to light at 555 nm. What color do you think is in the 555 nm wavelength? GREEN

9 CCTV SYSTEMS The wavelength of light determines it’s color. The longer wavelengths are at the red end of the spectrum, while the shorter wavelengths are towards the violet end of the spectrum. The wavelength of light determines it’s color. The longer wavelengths are at the red end of the spectrum, while the shorter wavelengths are towards the violet end of the spectrum.

10 CCTV SYSTEMS A camera, like the human eye, must receive light in this range in order to create a video image. Artificial light is produced by a number of processes, including heat, chemical reaction and photoelectrical activity. The most popular types of indoor lighting is incandescent and fluorescent lights. A camera, like the human eye, must receive light in this range in order to create a video image. Artificial light is produced by a number of processes, including heat, chemical reaction and photoelectrical activity. The most popular types of indoor lighting is incandescent and fluorescent lights.

11 CCTV SYSTEMS Outdoor lighting consists of halogen, high pressure sodium, metal halide, mercury and aluminum oxide lamps.

12 CCTV SYSTEMS Artificial lights, depending on the materials with which they are constructed, generate light at various wavelengths and therefore different colors.

13 CCTV SYSTEMS When measuring light we use photometric units. The basic measure of the amount of light produced by a light source or light output is the lumen, LED flashlights use this unit of measure. Another measure of light is called candlepower (CP) or simply put, a candle. When measuring light we use photometric units. The basic measure of the amount of light produced by a light source or light output is the lumen, LED flashlights use this unit of measure. Another measure of light is called candlepower (CP) or simply put, a candle.

14 CCTV SYSTEMS Candlepower was determined as the intensity of light emitted by a standardized candle at a distance of one foot and was expressed as a foot candle. The concept of candle (candlepower) was later replaced by the candela. Candlepower was determined as the intensity of light emitted by a standardized candle at a distance of one foot and was expressed as a foot candle. The concept of candle (candlepower) was later replaced by the candela.

15 CCTV SYSTEMS The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540×10 12 hertz and that has a radiant intensity in that direction of 1 ⁄ 683 watt per steradian (a solid angle). The candela is sometimes still called by the old name candle, such as in foot-candle and the modern definition of candlepower. The candela is the luminous intensity, in a given direction, of a source that emits monochromatic radiation of frequency 540×10 12 hertz and that has a radiant intensity in that direction of 1 ⁄ 683 watt per steradian (a solid angle). The candela is sometimes still called by the old name candle, such as in foot-candle and the modern definition of candlepower.

16 CCTV SYSTEMS A candela is a metric value and provides a much more precise and consistent measurement. The candela is based on the temperature of platinum where it converts from a liquid to a solid state. A candela is a metric value and provides a much more precise and consistent measurement. The candela is based on the temperature of platinum where it converts from a liquid to a solid state.

17 CCTV SYSTEMS When working with CCTV and video cameras, we have to take into account the reflectivity or illuminance of objects surfaces.

18 CCTV SYSTEMS When a light source hits an object, the amount of light reflected by the object determines what is seen by either the camera or the eye.

19 CCTV SYSTEMS Different materials reflect light to varying degrees. Snow reflects light up to 90% of the light that falls on it. Black velvet fabric reflects less than 20% of the light that falls on it The challenge with measuring reflectivity is that materials absorb some wavelengths while reflecting others. This is important when selecting or using a camera. Different materials reflect light to varying degrees. Snow reflects light up to 90% of the light that falls on it. Black velvet fabric reflects less than 20% of the light that falls on it The challenge with measuring reflectivity is that materials absorb some wavelengths while reflecting others. This is important when selecting or using a camera.

20 CCTV SYSTEMS A black and white camera is immune to spectral shifts. Color cameras are extremely sensitive to spectral shifts. The further away from a light source, the more the intensity of the light diminishes. A black and white camera is immune to spectral shifts. Color cameras are extremely sensitive to spectral shifts. The further away from a light source, the more the intensity of the light diminishes.

21 CCTV SYSTEMS When engineers, designers and manufacturers talk about reflectivity, they use a metric scale called lux.

22 CCTV SYSTEMS Lux is used to describe illumination, or the density of light falling on an object. Lux as defined in the dictionary……. Lux: is equal to the direct illumination on a surface that is everywhere one meter from a uniform point source of one candle intensity or equal to one lumen per square meter. Lux is used to describe illumination, or the density of light falling on an object. Lux as defined in the dictionary……. Lux: is equal to the direct illumination on a surface that is everywhere one meter from a uniform point source of one candle intensity or equal to one lumen per square meter.

23 CCTV SYSTEMS When we are talking about illumination or lux, we are referring to the actual light available at a given distance.

24 CCTV SYSTEMS Lumens are used to measure how much light is produced by a light source. Lux and foot candles are equivalent measures, they both measure the same thing, but use different scales. Use these two rules to convert between lux and foot candles, a foot candle is lux and a lux is foot candles. Lumens are used to measure how much light is produced by a light source. Lux and foot candles are equivalent measures, they both measure the same thing, but use different scales. Use these two rules to convert between lux and foot candles, a foot candle is lux and a lux is foot candles.

25 CCTV SYSTEMS Lux is equal to one lumen per square meter. Lux is the unit of measurement used by cameras, the lower the lux rating the better the camera can see in low light. Lux is equal to one lumen per square meter. Lux is the unit of measurement used by cameras, the lower the lux rating the better the camera can see in low light.

26 CCTV SYSTEMS Most CCD cameras are sensitive to light ranging from bright sunlight (10,000 foot candles, or 107,500 lux) to twilight (1 foot candle, or 10.7 lux) This means a camera can operate in relatively high or low light levels. Special cameras that are low light sensitive are called LLL cameras, and are extremely expensive. Most CCD cameras are sensitive to light ranging from bright sunlight (10,000 foot candles, or 107,500 lux) to twilight (1 foot candle, or 10.7 lux) This means a camera can operate in relatively high or low light levels. Special cameras that are low light sensitive are called LLL cameras, and are extremely expensive.

27 CCTV SYSTEMS Another solution for a dark CCTV environment is the use of infrared light sources and infrared sensitive cameras. Infrared light (IR) is light below the threshold of human vision. Another solution for a dark CCTV environment is the use of infrared light sources and infrared sensitive cameras. Infrared light (IR) is light below the threshold of human vision.

28 CCTV SYSTEMS the IR spectrum is separated into two categories, near infrared and far infrared ranging from 800nm to 6,000nm.

29 CCTV SYSTEMS Near infrared ranges from 800nm to 3,000nm. Infrared sensitive cameras use the infrared wavelengths between 800nm to 900nm. Light in this range behaves as visible light and can illuminate a scene for surveillance. Light in this range is undetectable to the human eye. Near infrared ranges from 800nm to 3,000nm. Infrared sensitive cameras use the infrared wavelengths between 800nm to 900nm. Light in this range behaves as visible light and can illuminate a scene for surveillance. Light in this range is undetectable to the human eye.

30 CCTV SYSTEMS Infrared can be detected by instrumentation designed for visible light. There are two types of infrared sensitive cameras. The first type of infrared camera requires an external IR light source. The second type of IR sensitive camera amplifies existing light. Infrared can be detected by instrumentation designed for visible light. There are two types of infrared sensitive cameras. The first type of infrared camera requires an external IR light source. The second type of IR sensitive camera amplifies existing light.

31 CCTV SYSTEMS Cameras that require an external IR light source use an array of led lights to produce infrared light in the range of 900nm to 1,100nm. Zero lux cameras contain a CCD for imaging, and some cameras are designed with an infrared led array built into the camera housing. Cameras that require an external IR light source use an array of led lights to produce infrared light in the range of 900nm to 1,100nm. Zero lux cameras contain a CCD for imaging, and some cameras are designed with an infrared led array built into the camera housing.

32 CCTV SYSTEMS The challenge is to produce enough light to illuminate a scene. Cameras with built-in infrared LED’s typically have a short illumination distance of only feet. To increase the distance, an external infrared illuminator is required. The challenge is to produce enough light to illuminate a scene. Cameras with built-in infrared LED’s typically have a short illumination distance of only feet. To increase the distance, an external infrared illuminator is required.

33 CCTV SYSTEMS External infrared illuminators come in varieties: Infrared led array…already mentioned Special high intensity lamps with a visible light filter, lamps with filters can still emit visible light of 0.01 lux. LED arrays are state of the art in lighting, and are most likely to be used today. External infrared illuminators come in varieties: Infrared led array…already mentioned Special high intensity lamps with a visible light filter, lamps with filters can still emit visible light of 0.01 lux. LED arrays are state of the art in lighting, and are most likely to be used today.

34 CCTV SYSTEMS For typical CCTV applications, we are looking for cameras that can serve dual lighting purposes. We want a camera that works with both visible light to zero to no light. These cameras are called night vision or zero lux cameras. For typical CCTV applications, we are looking for cameras that can serve dual lighting purposes. We want a camera that works with both visible light to zero to no light. These cameras are called night vision or zero lux cameras.

35 CCTV SYSTEMS Night vision cameras work by first converting the incoming light into an electrical signal. The signal is then amplified and converted back into light. When available light is converted for use by a CCTV camera, it is converted into green light. Night vision cameras work by first converting the incoming light into an electrical signal. The signal is then amplified and converted back into light. When available light is converted for use by a CCTV camera, it is converted into green light.

36 CCTV SYSTEMS Remember that green light is right in the middle of the visible spectrum and the human eye is most sensitive to green light. By converting to green, the range of amplification is greater, for this reason, images from low light cameras are usually green. Red and blue both have narrow wavelength bands in comparison. Remember that green light is right in the middle of the visible spectrum and the human eye is most sensitive to green light. By converting to green, the range of amplification is greater, for this reason, images from low light cameras are usually green. Red and blue both have narrow wavelength bands in comparison.

37 CCTV SYSTEMS Some cameras switch from color to black and white to capture images during dawn and dusk hours.

38 CCTV SYSTEMS One problem with available light cameras generate a certain amount of visual noise or visual artifacts during the conversion process. Because they amplify available light, light from sources such as the moon or street lights may actually be too bright to capture. Most cameras provide automatic gain control (AGC), which allows the camera to compensate by adjusting its sensitivity. One problem with available light cameras generate a certain amount of visual noise or visual artifacts during the conversion process. Because they amplify available light, light from sources such as the moon or street lights may actually be too bright to capture. Most cameras provide automatic gain control (AGC), which allows the camera to compensate by adjusting its sensitivity.

39 CCTV SYSTEMS The images provided are more useful, but details in shadow areas can be blacked out as a result.

40 CCTV SYSTEMS Backlighting can be an unwanted effect in CCTV, it means that you have a video image where the details are blacked out because of a bright light source behind the object you’re viewing. To solve this cameras provide either a backlight compensation (BLC) or automatic light control (ALC) adjustment. Backlighting can be an unwanted effect in CCTV, it means that you have a video image where the details are blacked out because of a bright light source behind the object you’re viewing. To solve this cameras provide either a backlight compensation (BLC) or automatic light control (ALC) adjustment.