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Six tips for choosing security camera

Sep 16, 2017

wireless security camera system

1, the lens type (classification according to the application)


Wide-angle lens: angle of view of 90 degrees or more, a large observation area near the image deformation.


Standard Lens: approximately 30 degrees angle of view, a wider range of use.


Telephoto lens: angle of view of 20 degrees or less, the focal length of up to tens or hundreds of millimeters mm.


Zoom: a continuously variable focal length lens, the focal length can be changed from the wide angle to the telephoto, the greater the longer the focal length imaging.


Pinhole lens: for covert observation, and the like are often installed in places such as a ceiling or wall.


2, the relationship between the size of the subject object, the focal distance


Suppose the width and height are the subject w.h, the subject distance between the object and the focal length of the lens L, the lens is f.


3, relative aperture


To control the size of the luminous flux of the lens, a rear lens aperture are provided. Assuming the effective aperture diaphragm is d, because of light refraction, mirror light practical and effective effective pore diameter d, is greater than d, ratio is defined as d and the focal length f of the relative aperture of a, relatively i.e., a = d / f, lens aperture determines the imaging illumination, like the reciprocal of the relative aperture of the illumination lens to represent the size of the lens aperture. f value, the larger the aperture, the light flux reaches the greater ccd chip. Therefore, in the case of the same focal length f, f smaller value indicates a better shot.


4, the lens focal length


1) Focal length: fixed focal length, and aperture may be divided into two kinds without aperture.


An aperture: the size of the lens aperture can be adjusted. The changes in the environment according to the river, the size of the aperture should be adjusted accordingly. The size of the aperture can be adjusted manually or automatically, adjusting the aperture of the human hand, known as manual iris. Lens comes automatically adjusts the aperture micro-motor, called auto iris.


No aperture: i.e. fixed aperture, which is the amount of light is fixed. The light source is mainly used for the case of constant or an electronic shutter of the camera itself.


2) Zoom: focal length can be adjusted as necessary to make the subject image enlargement or reduction. The zoom lens is used six times, ten sale of zoom.


Three variable and two variable lens


Three variable lens: adjustable focus, focus adjustment, aperture adjustment.


Two variable lens: a focus adjustment, focus adjustment, auto iris.


5, the principle of choose lens firstly


In order to achieve the desired camera effects, while matching the camera, we should focus on six basic elements:


a) the size of the object subject


B) the details of the subject


C) Object distance


D) focal length


E) Dimensions of the ccd camera target surface


F) resolution of lens and camera system


The lens focal length covering the subject is calculated by the following formula.


F = v * D / V (1) f = h * D / H (2)


F: lens focal length


V: photographing scene vertical height


H: Length of the landscape in the vertical direction


D: distance between the lens to the shooting scene


V: vertical height of the camera screen


H: Horizontal height of the camera screen (1) Measure the height of the shooting scene


1/2 type camera (screen size) v = 4.8mm


Shooting scene vertical direction height V = 330mm (33cm)


Lens to the distance between the shooting scene D = 2500mm (250cm)


In equation (1)


Seen f = 36mm


(2) measuring the length of the scene photographed


1/2 cameras (screen size) h = 6.4mm


The horizontal direction of the scene is H = 440mm (44cm)


Distance from the lens to the shooting scene D = 2500mm (250cm)


Into the formula (2)


Note: In practice, the field of view based on the value derived from V and H may be different, it should take a smaller value, so that a larger field of view.


6, the steps:


Remove the lens anti-tip device, connect the lens.


If you use the cs lens, please lower c ring (5mm), and then lock the cs lens device.


c-type lenses can be mounted directly.


Video output connector (BNC) to the monitor or other devices.


Powered by dc12v / ac220v * and check if the led light is on.


Once the image is blurred, adjust the lens focal length.

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