1, the type of lens (according to the application category)
Wide-angle lens: The angle of view is more than 90 degrees, the observation range is larger in the vicinity of the image deformation; the standard lens: the angle of view is about 30 degrees, the use of a wide range; telephoto lens: within 20 degrees of viewing angle, the focal length of up to tens of millimeters or hundreds of millimeters; Zoom Lens: The focal length of the lens is continuously variable, and the focal length can be changed from wide-angle to telephoto. The longer the focal length is, the larger the image is; the pinhole lens is used for concealed observation and is often installed in a place such as a ceiling or a wall.
2. The relationship between the size, distance, and focal length of the subject
Assume that the width and height of the subject are respectively wh, the distance between the subject 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 passing through the lens, an aperture is provided 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 and the focal length f is defined as the relative aperture a, that is, a=d/f, the relative of the lens The aperture determines the illuminance of the captured image, and the illuminance of the image and the inverse of the relative aperture of the lens represent the aperture of the lens. The smaller the f-number, the larger the aperture, the greater the luminous flux reaching the ccd chip. Therefore, in the case of the same focal length f, the smaller the value of f, the better the lens.
4, the focal length of the lens 1) fixed focus: the focal length is fixed, can be divided into two kinds of aperture and no aperture.
Aperture: The lens aperture can be adjusted in size. According to changes in the environment, the aperture should be adjusted accordingly. The size of the aperture can be adjusted manually or automatically. Manually adjusting the aperture is called a manual aperture. The lens comes with a micro motor that automatically adjusts the aperture, called the auto iris.
No aperture: fixed aperture, the amount of light is fixed. It is mainly used when the light source is constant or the camera comes with an electronic shutter.
2) Zoom: The focal length can be adjusted as needed to make the image of the subject zoom in or out. The commonly used zoom lens is a six-fold, ten-sale zoom.
Three variable and two variable lenses; three variable lenses: adjustable focal length, adjustable focus, adjustable lens; two variable lenses: adjustable focus, adjustable focus, and automatic aperture.
5, the first lens with the principle of <br> <br> camera in order to obtain the desired effect, in matching lens, should focus on six basic elements:
The size of the subject; the detail size of the subject; object distance; focal length; the size of the ccd camera's target surface; the resolution of the lens and camera system.
The focal length of the lens covering the scene being shot can be calculated by the following formula:
f=v*D/V(1)
f=h*D/H(2)
f: the lens focal length; V: the height of the subject in the vertical direction; H: the length of the subject in the vertical direction; D: the distance from the lens to the subject; v: the vertical height of the camera screen; h: the horizontal direction of the camera screen Height (1) Measurement Scenery Height 1/2 Camera (Screen Size); v = 4.8mm Vertical Scene Height V = 330mm (33cm); Lens to Scene Distance D = 2500mm (250cm) Substituted in Formula (1) ) It can be seen that f=36mm (2) Measurement of the length of the shooting scene 1/2-type camera (frame size) h = 6.4mm, the horizontal length of the shooting scene; H = 440mm (44cm); distance from the lens to the shooting scene D = 2500mm (250cm), substituting the formula (2).
Note: In practical applications, the values ​​derived from V and H depending on the field of view may not be the same and should take a smaller value to obtain a larger field of view.
6, the steps:
Remove the lens tip and connect the lens. If you use a cs lens, lower c circle (5mm) and lock the cs lens assembly. C-type lens can be installed directly. Connect the video output (bnc) to a monitor or other device. Plug in the dc12v power/ac220v* and 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, the observation range is larger in the vicinity of the image deformation; the standard lens: the angle of view is about 30 degrees, the use of a wide range; telephoto lens: within 20 degrees of viewing angle, the focal length of up to tens of millimeters or hundreds of millimeters; Zoom Lens: The focal length of the lens is continuously variable, and the focal length can be changed from wide-angle to telephoto. The longer the focal length is, the larger the image is; the pinhole lens is used for concealed observation and is often installed in a place such as a ceiling or a wall.
2. The relationship between the size, distance, and focal length of the subject
Assume that the width and height of the subject are respectively wh, the distance between the subject 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 passing through the lens, an aperture is provided 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 and the focal length f is defined as the relative aperture a, that is, a=d/f, the relative of the lens The aperture determines the illuminance of the captured image, and the illuminance of the image and the inverse of the relative aperture of the lens represent the aperture of the lens. The smaller the f-number, the larger the aperture, the greater the luminous flux reaching the ccd chip. Therefore, in the case of the same focal length f, the smaller the value of f, the better the lens.
4, the focal length of the lens 1) fixed focus: the focal length is fixed, can be divided into two kinds of aperture and no aperture.
Aperture: The lens aperture can be adjusted in size. According to changes in the environment, the aperture should be adjusted accordingly. The size of the aperture can be adjusted manually or automatically. Manually adjusting the aperture is called a manual aperture. The lens comes with a micro motor that automatically adjusts the aperture, called the auto iris.
No aperture: fixed aperture, the amount of light is fixed. It is mainly used when the light source is constant or the camera comes with an electronic shutter.
2) Zoom: The focal length can be adjusted as needed to make the image of the subject zoom in or out. The commonly used zoom lens is a six-fold, ten-sale zoom.
Three variable and two variable lenses; three variable lenses: adjustable focal length, adjustable focus, adjustable lens; two variable lenses: adjustable focus, adjustable focus, and automatic aperture.
5, the first lens with the principle of <br> <br> camera in order to obtain the desired effect, in matching lens, should focus on six basic elements:
The size of the subject; the detail size of the subject; object distance; focal length; the size of the ccd camera's target surface; the resolution of the lens and camera system.
The focal length of the lens covering the scene being shot can be calculated by the following formula:
f=v*D/V(1)
f=h*D/H(2)
f: the lens focal length; V: the height of the subject in the vertical direction; H: the length of the subject in the vertical direction; D: the distance from the lens to the subject; v: the vertical height of the camera screen; h: the horizontal direction of the camera screen Height (1) Measurement Scenery Height 1/2 Camera (Screen Size); v = 4.8mm Vertical Scene Height V = 330mm (33cm); Lens to Scene Distance D = 2500mm (250cm) Substituted in Formula (1) ) It can be seen that f=36mm (2) Measurement of the length of the shooting scene 1/2-type camera (frame size) h = 6.4mm, the horizontal length of the shooting scene; H = 440mm (44cm); distance from the lens to the shooting scene D = 2500mm (250cm), substituting the formula (2).
Note: In practical applications, the values ​​derived from V and H depending on the field of view may not be the same and should take a smaller value to obtain a larger field of view.
6, the steps:
Remove the lens tip and connect the lens. If you use a cs lens, lower c circle (5mm) and lock the cs lens assembly. C-type lens can be installed directly. Connect the video output (bnc) to a monitor or other device. Plug in the dc12v power/ac220v* and check if the led is on. When the image is blurred, adjust the lens focal length.
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