Black USB Dash Camera Dustproof 12V USB Rear View Camera High Definition

Reverse image truck wide angle infrared night vision high - definition camera USB rear view camera

Universal camera  .
General purpose cameras include 18.5mm perforated cameras    small butterfly external cameras    license plate frame came   28mm perforated cameras   bus cameras     and other external cameras   such as LED night vision color external cameras for car navigators
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The lens of the car mounted camera is the core component    and the four key parameters are as follows  

Folding focal length

The size of the focal length determines the size of the field of view angle .  When the focal length value is small    the field of view angle is large   and the observed range is also large   but the resolution of distant objects is not very clear   The focal length value is large   the field of view angle is small, and the observation range is small  .  As long as the focal length is selected appropriately    even distant objects can be seen clearly  .   Due to the one-to-one correspondence between focal length and field of view angle    a determined focal length means a determined field of view angle  .   Therefore    when selecting a lens focal length    it is important to fully consider whether the observation details are important or whether a large observation range is important. If you want to see details    choose a long focal length lens     If you are watching close -  up scenes    choose a wide -  angle lens with a small focal length . 

Folding aperture coefficient
The car mounted camera    also known as the light flux    is represented by F and measured by the ratio of the lens focal length f to the aperture D .  Each lens is labeled with a maximum F value, for example   6mm/F1.4 represents a maximum aperture of 4.29 millimeters  .   The luminous flux is inversely proportional to the square of the F -  value   and the smaller the F -  value    the greater the luminous flux .  The scale values of the aperture index sequence on the lens are 1.4     2    2.8     4      5.6    8    11    16     22    etc   . The pattern is that the exposure amount at the previous scale value is exactly twice that of the corresponding exposure amount at the latter scale value .  That is to say     the aperture of the lens is 1/1.4    1/2    1/2.8    1/4     1/5.6     1/8     1/11     1/16    1/22     respectively    The former value is twice the root of the latter value  . Therefore    the smaller the aperture index     the larger the aperture     and the greater the illumination on the imaging target surface   .  In addition    t

Folding automatic aperture lens
The automatic aperture lens of car mounted cameras can be divided into two categories  :   one is called the video (VIDEO) drive type   and the lens itself contains an amplifier circuit to convert the video amplitude signal transmitted by the camera into control of the aperture motor .  Another type is called DC drive type    which uses the DC voltage on the camera to directly control the aperture   This type of lens only includes an ammeter type aperture motor and requires an amplifier circuit inside the camera  .   For various types of automatic aperture lenses   there are usually two adjustable knobs .   One is the ALC adjustment (metering adjustment)    which has two options     peak metering and average metering based on target lighting conditions  .  Generally   the average metering level is taken     Another is LEVEL adjustment (sensitivity)   which can make the output image bright or dim .

Folding zoom lens
Car mounted camera zoom lenses are divided into two types :  manual zoom lenses and electric zoom lenses .  Manual zoom lenses are generally used for scientific research projects rather than in closed - loop monitoring systems .  When monitoring large scenes   the camera usually needs to be used in conjunction with an electric lens and pan tilt  .  The advantage of an electric lens is that it has a large zoom range, which allows for viewing a wide range of situations and focusing on certain details  . In addition    the pan tilt can rotate up    down    left   and right   resulting in a very large viewing range   .   Electric lenses have multiple magnifications such as 6x   10x   15x    20x   etc    If you know the reference focal length    you can determine the variable range of the lens focal length   For example    a 6x electric lens with a reference focal length of 8.5 millimeters would have a continuously adjustable zoom range of 8.5 to 51 millimeters and a field of view angle of 31.3 to 5.5 degrees 

In addition to the above four items    there are certainly other minor knowledge     but mastering these four indicator coefficients can be suitable for the configuration and application of the lens