Friends who contact the autofocus camera know that we often see the word “minimum illumination” in the specification parameters of SONY integrated movement or other cameras. So today, Shenzhen Xuan Zhan Technology will share the knowledge about the minimum illumination for you, hoping to help you in the future when using the movement.
Illuminance is expressed in Lux. Generally speaking, the camera is usually at 0Lux or 0.1Lux. The illumination value depends on the aperture size of the lens (F value: F value is the ratio of the lens focal length to the aperture diameter; the smaller the ratio, the larger the aperture and the greater the light transmission). The smaller the F value, the lower the illumination required.
Cameras from 0.001Lux to 1Lux, opinions vary, when the Lux value at 0.001, basically has reached starlight.
As the name implies, low illuminance camera refers to the camera that can still take clear images under the condition of low illuminance. There is no unified standard for this in the technical specifications of CCTV industry, so it is not possible to define why the lowest illuminance can be called a low illuminance camera. Besides the lowest illuminance value with the size of the aperture of the lens (F value), ELECTRONIC SENSITIVITY (ELECTRONIC, SENSITIVITY), infrared switch state conditions have relations, so need to examine the camera in the same test conditions minimum illumination.
Minimum illumination is also called sensitivity. It is the sensitivity of the CCD to ambient light, or the darkest light required by the CCD for normal imaging. Intensity of illumination is the unit of lux, the smaller the value, said need less light, cameras are more sensitive. The sensitivity of black and white cameras is about 0.02-0.5lux(Lux) color cameras are more than 1lux. Cameras of 0.1lux are used for ordinary surveillance occasions; A 0.02lux camera is recommended for use at night or in low ambient light. Low illumination cameras must also be used in conjunction with near red lights.
We know that the minimum illuminance is actually a measure of the camera’s sensitivity, in other words, how dark the camera can see the usable image.
The most commonly used method to measure the minimum illuminance is called the target illuminance method. The target illuminance indicates how much light reaches the surface of the CCD. Although clearly defined differently, there are three main parameters that determine the outcome.
F rest (lens F rest for testing camera)
Color temperature (the color temperature of the light source, that is, the spectral content)
IRE (IRE level of video amplitude)
Reflectance (reflectance and background of the target)
A good lens can collect more light and focus it on the CCD sensor. The lens of F1.4 can collect 2 times more light than that of F2.0. In other words, the lens of F1.0 can collect 100 times more light than that of F10. Otherwise the results are meaningless.
Color temperature is a measure of the wavelength content of the light source, a 3200K light source most of the wavelength is between 600 nanometers, and a 9300K light source most of the wavelength is between 300 and 500 nanometers, so different color temperature will drastically change the test results, this is worth noting.