In this section you can find the most frequently asked questions on CCTV illumination. The brevity of questions do not allow us to make them exhaustive enough. For more information on CCTV illumination you can refer to other sections of our site.
Why do we use IR illumination in CCTV?
IR radiation is nearly invisible for human eye but the bulk of black-and-white video cameras and Day/Night cameras are infrared-sensitive. It allows to use IR illuminators for CCTV during nighttime. IR illuminators on the basis of light-emitting diodes have good chracterisctics of power consumption and considerable life time. They also allow covert surveillance.
Is it possible to use IR illumination together with color-video camera?
IR illumination can not be used together with color-video cameras. Color-video cameras have built-in filters which are IR insensitive. It is done to ensure correct color rendition. IR illumination can work together with modern Day/Night cameras where IR filter is is mechanically removed in night mode.
Can any black-and-white video camera work with IR illumination?
The majority of black-and-white video cameras have good IR sensitivity. However for absolute certainty it is necessary to inquire the manufacturer about it or make sure by experiment that the camera is IR sensitive.
What is the range of the camera with an IR illumination?
The illumination range depends on many factors: sensitivity and spectral characteristics of video cameras, lens quality, glass quality of sealed casing, power and main wavelength of IR illuminator, reflection power of object under observation in IR band etc.
What is the difference between IR illuminators on the basis of glow lamps and IR diodes?
IR illuminators on the basis of halogen lamps and light filters have a significantly lower coefficient of efficiency and short mean time between failures in comparison with illuminators on the basis of IR diodes. The necessity to frequently change lamps and significant power consumption make illuminators on the basis of glow lamps economically inefficient for CCTV illumination. All modern IR illuminators are made on the basis of IR diodes.
What is the difference between IR illuminators with different wavelength?
As a rule IR illuminators have a medium wavelength from 720 to 940 nm. At the same radiation power (do not mix up with consumption power) and radiation angle, illuminators with a shorter wavelength are more efficient, as far as camera sensitivity falls with the growth of wavelength. For hidden illumination it is necessary to use illuminators with wavelength of 940 nm. Illuminators with wavelength of 850-880 nm. can ensure only “half-hidden” illumination – when looking at the illuminator itself one can see faint red glow. It is inadmissible at motorways, railways etc. IR illuminators with wavelength of 720-780 nm. are used quite seldom because light-emitting diode chips are usually less efficient at such wavelength.
Can IR illumination be used for covert surveillance?
Yes. IR illuminators with wavelength of more than 920 nm. are invisible to the naked eye and can be used for hidden illumination. When using illuminators with wavelength of 850-880 nm. one can not see the radiation which falls on the surrounding objects but if looking at the illuminator itself one can see faint red glow.
How does the lens influence the work of camera with IR illumination?
Lens aperture (F) influences the camera sensitivity in visible-light spectrum as well as in IR spectrum. The less is the value of F, the more sensitive is the system camera + lens. As for today lenses produced for CCTV cameras are specially adapted to working in IR band.
How does the sealed casing influence the work of camera with IR illumination?
The sealed casing, where the camera is placed when installed outdoors, can have glass with low IR transmission. The majority of modern sealed casings do not have this deficiency and this should be taken into account when choosing equipment.