[ Huaqiang Security Network News ] Quickly master security monitoring to teach you six tips 1, the type of lens (according to the application category)
Wide-angle lens: The angle of view is more than 90 degrees, and the image is deformed near the larger observation range.
Standard lens: The viewing angle is about 30 degrees, and the range of use is wide.
Telephoto lens: The viewing angle is within 20 degrees, and the focal length can reach several tens of millimeters or hundreds of millimeters.
Zoom lens: The focal length of the lens is continuously variable, the focal length can be changed from wide angle to telephoto, and the longer the focal length, the larger the imaging.
Pinhole lens: used for concealed observation, often installed in places such as ceilings or walls.
2. The relationship between the size, distance and focal length of the subject assumes that the width and height of the object are wh, the distance between the object and the lens is l, and the focal length of the lens is f.
3. Relative aperture In order to control the amount of light flux through the lens, an aperture is placed at the rear of the lens. Assuming that the effective aperture of the aperture is d, due to the relationship of light refraction, the effective effective aperture of the mirror light is d, which is larger than d, and the ratio of d to focal length f is defined as the relative aperture a, ie, a=d/f, the relative of the lens. The aperture determines the illuminance of the image, and the illuminance of the image and the reciprocal of the relative aperture of the lens represent the size of the lens aperture. The smaller the f value, the larger the aperture and the greater the luminous flux reaching the ccd chip. Therefore, in the case where the focal length f is the same, the smaller the f value, the better the lens.
4, the focal length of the lens
1) Fixed focal length: The focal length is fixed and can be divided into two types: aperture and no aperture.
There is aperture: the size of the lens aperture can be adjusted. According to the changes in the environment, the size of the aperture should be adjusted accordingly. The size of the aperture can be adjusted manually or automatically, and the aperture is manually adjusted manually, called the manual aperture. The lens comes with a micro motor that automatically adjusts the aperture, called the auto iris.
No aperture: the aperture is fixed, and the amount of light passing through it is fixed. It is mainly used when the light source is constant or the camera has its own electronic shutter.
2) Zoom: The focal length can be adjusted as needed to enlarge or reduce the image of the subject. The commonly used zoom lens is a six-fold, ten-sale zoom.
Three variable and two variable lens three variable lenses: adjustable focus, focus, dimming.
Two variable lenses: adjustable focus, focus, auto iris.
5, the first lens principle In order to obtain the expected camera effect, when selecting the lens, we should pay attention to six basic elements:
a) the size of the subject
b) the size of the subject
c) object distance
d) focal length
e) ccd camera target size
f) Resolution of the lens and camera system
6, the operation steps:
Remove the lens tip guard and attach the lens.
If using a cs lens, lower the c-ring (5mm) and lock the cs lens unit.
The c-type lens can be installed directly.
Connect the video output (bnc) to a monitor or other device.
Plug in the dc12v power supply / ac220v * check if the led is on.
When the image is blurred, adjust the lens focal length.
Wide-angle lens: The angle of view is more than 90 degrees, and the image is deformed near the larger observation range.
Standard lens: The viewing angle is about 30 degrees, and the range of use is wide.
Telephoto lens: The viewing angle is within 20 degrees, and the focal length can reach several tens of millimeters or hundreds of millimeters.
Zoom lens: The focal length of the lens is continuously variable, the focal length can be changed from wide angle to telephoto, and the longer the focal length, the larger the imaging.
Pinhole lens: used for concealed observation, often installed in places such as ceilings or walls.
2. The relationship between the size, distance and focal length of the subject assumes that the width and height of the object are wh, the distance between the object and the lens is l, and the focal length of the lens is f.
3. Relative aperture In order to control the amount of light flux through the lens, an aperture is placed at the rear of the lens. Assuming that the effective aperture of the aperture is d, due to the relationship of light refraction, the effective effective aperture of the mirror light is d, which is larger than d, and the ratio of d to focal length f is defined as the relative aperture a, ie, a=d/f, the relative of the lens. The aperture determines the illuminance of the image, and the illuminance of the image and the reciprocal of the relative aperture of the lens represent the size of the lens aperture. The smaller the f value, the larger the aperture and the greater the luminous flux reaching the ccd chip. Therefore, in the case where the focal length f is the same, the smaller the f value, the better the lens.
4, the focal length of the lens
1) Fixed focal length: The focal length is fixed and can be divided into two types: aperture and no aperture.
There is aperture: the size of the lens aperture can be adjusted. According to the changes in the environment, the size of the aperture should be adjusted accordingly. The size of the aperture can be adjusted manually or automatically, and the aperture is manually adjusted manually, called the manual aperture. The lens comes with a micro motor that automatically adjusts the aperture, called the auto iris.
No aperture: the aperture is fixed, and the amount of light passing through it is fixed. It is mainly used when the light source is constant or the camera has its own electronic shutter.
2) Zoom: The focal length can be adjusted as needed to enlarge or reduce the image of the subject. The commonly used zoom lens is a six-fold, ten-sale zoom.
Three variable and two variable lens three variable lenses: adjustable focus, focus, dimming.
Two variable lenses: adjustable focus, focus, auto iris.
5, the first lens principle In order to obtain the expected camera effect, when selecting the lens, we should pay attention to six basic elements:
a) the size of the subject
b) the size of the subject
c) object distance
d) focal length
e) ccd camera target size
f) Resolution of the lens and camera system
6, the operation steps:
Remove the lens tip guard and attach the lens.
If using a cs lens, lower the c-ring (5mm) and lock the cs lens unit.
The c-type lens can be installed directly.
Connect the video output (bnc) to a monitor or other device.
Plug in the dc12v power supply / ac220v * check if the led is on.
When the image is blurred, adjust the lens focal length.
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