A CMOS sensor is a sensor that is typically 10 times slower than a CCD sensor. Because the human eye can see the target below 1 Lux illumination (full moon night), the CCD sensor can usually see slightly better than 0. 1 to 3 Lux, which is 3 to 10 times faster than the CMOS sensor.

Lens Analysis

1. Type of lens (categorized according to application)

       Wide-angle lens: The angle of view is more than 90 degrees. The observation range is larger and the image is distorted.

       Standard lens: The angle of view is about 30 degrees, and the range of use is wider.

       Telephoto lens: within 20 degrees of viewing angle, focal lengths 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, the larger the image.

       Pinhole lenses: Used for concealed observations, often mounted in places such as ceilings or walls.

2. The relationship between the size, distance, and focal length of the subject

       Assume that the width and height of the subject are W, respectively. H, 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 greater than d, the ratio of D to 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 value of F, 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 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.

       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. 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 focus, focus, and zoom.

       Two variable lenses: adjustable focus, focus, auto iris.

5. First lens principle

       In order to obtain the desired camera effect, when selecting the lens, pay attention to six basic elements: A) The size of the subject B) The detail size of the subject C) The object distance D) The focal length E) The CCD camera The target Size F) Lens and Camera System Resolution

       Procedure: Remove the lens tip and connect the lens. If using a CS lens, lower the C ring (5mm) and lock the CS lens unit. C-type lens can be installed directly. Connect the video output (BNC) to a monitor or other device. Plug in DC12V power/AC220V to check if the LED is on. When the image is blurred, adjust the lens focal length.

       Lens C-Interface and CS-Interface Differences: Lens Mounting Classification All camera lenses are threaded, and the CCD camera lens mounts two industry standards, the C mount and the CS mount. Both threads have the same part, but they have different distances from the lens to the photosensitive surface. C mount: The distance from the lens mount reference surface to the focus is 17.526 mm. CS mount: Special C mount. At this time, remove the washer on the front of the camera and install the lens. The distance from the lens mounting plane to the focus is 12. 5mm. If a C mount lens is to be mounted on a CS mount camera, a lens converter is required.