What is the purpose of lenses in a camera

What is the purpose of lenses in a camera

The camera lens is the key equipment of video system, its quality directly affects the whole  index of the camera , camera lens is the equivalent of the human eye lens, if there is no lens, the eye can not see any object; if there is no cctv lens, then the camera can not output image; is a piece of white, no clear image output .the principle of this is the same with our home video camera .

Classification of camera lenses

Classification based on structure of camera lenses

Fixed aperture fixed focus camera lens. The lens is only one can manually adjust the focusing ring, rotating around the ring can make the image on the CCD target surface clearly. No aperture adjustment ring, the aperture can not adjust the flux into the lens .The structure is simple, the price is cheap.

Manual iris camera lens: manual aperture lens increases the aperture adjustment ring rather than fixed aperture lens, aperture range from F1.2 or F1.4 to the fully closed, can easily adapt to be photographed the scene light illumination. aperture is adjusted manually by human. Light illumination is more uniform, the price is cheaper.

Auto iris cctv lens: micro motor in the aperture adjustment ring Manual Iris lenses on a gear drive, and leads to the 3 or 4 core shielded wire from the drive circuit to the camera automatic aperture interface base. When the change of luminous flux into the lens of the camera, the charge on CCD target have changed, so that the video signal level change, a control signal is generated to the auto iris lens, so that the motor inside the lens corresponding forward or reverse rotation, adjust the size of the task completed

Manual aperture fixed focal lens: a variable focal length, there is a focal length adjustment ring, you can adjust the focal length of the lens in a certain range, the variable ratio is generally 2 to 3 times, the focal length is generally 3.6~8mm. In practical application, it is easy to choose the market angle of the monitored market through the manual adjustment of the zoom ring of the lens. But when the camera installation position is fixed, it is not convenient to manually adjust the zoom. Therefore, after the project is completed, the focal length of the manual zoom lens is generally very little. Only the role of fixed focus lens

Automatic aperture zoom lens: increase compared with the automatic iris lenses two micro motor, one motor and the zoom lens when it rotates the cyclization, can control the focal length of the lens; a motor and lens focus when the controlled cyclization, rotation can complete lens focusing. However, due to the increase of the number of two motor and lens group, the volume of the lens increases accordingly. 6 electric three variable lenses and automatic aperture electric zoom lens compared to the control of the aperture to adjust the motor is controlled by the automatic control to the ground by the controller to manually control.

Classification based on using occasion of camera lens

According to FOV : small field lens ,normal lens (about 50 degrees), wide-angle lens and super wide-angle lens (100-125 degrees).

Standard cctv lens: visual angle of about 50 degrees, but also people in the head and eye does not turn the eye can see the perspective of the object, so also known as the standard cctv lens.

Wide angle lens: the angle of view is more than 90 degrees, it is suitable for the scene which is close to the distance and the scope is big, but also can exaggerate the prospect to display the strong sense of far and near.

Telephoto lens: suitable for shooting distance scenery, small depth of field easily blurred background subjects, but the volume of heavy and dynamic focusing is not easy.

Macro lens: in addition to be very close to the macro photography, or telephoto

Classification based on Interface type

 C mount lens  cs mount lens  m12 mount lens  m8 lens

Main features of the camera lens

Lens multiple (zoom ~x)

A combination of an optical zoom lens and a digital zoom lens produces a maximum magnification

Resolution (Lines ~TV)

The value represents the ability of the camera to process details. The resolution of the test is done by a test graph with an increasingly dense line cluster. The value is the resolution of the dense line in the camera image can distinguish the maximum value of a single line of the region, the resolution of the commonly used television scanning line, the higher the value of the camera's image quality is better

focal length:Is the distance between the focal point of the lens and the lens.

Zoom (ZOOM):Used to zoom in and out of the object

Focus (FOCUS):Used to fine tune the object to achieve the best visual effect.

How to clean camera lens

Camera Lenses are particularly prone to dirty, but can not often wipe off the lens of the dust, the surface of the lens sheet has a protective film, often wipe the lens will destroy the organization. If the lens is stained with dust, do not use towels, paper towels and other items to wipe. Through a "paper tiger" (i.e. blowing balloons) will blew the dust off the lens surface of the use of air. The use of air blowing ball sometimes does not completely blow off the dust, if the dust on the lens is not a lot of words, the dust will not affect the picture quality.