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Lens control. Once the field of view is determined for the scene of interest, you need to focus the objects in the scene sharply. Use focus control for this. Make sure that field of depth is related to aperture. When you use auto iris, the installation is done during the day time, when the auto iris is tightly closed, thus giving a deeper field of depth. But during the night time, the auto iris opens up, which narrows the field of view. This results in objects becoming fuzzy and out of focus. Use ND filters during the installation to decrease the amount of light passing through the camera lens, which forces the camera to open up the auto iris, and the depth of field becomes narrow enough to prevent the focus drift during the night or low light condition.
Lens control. Zoom controls the viewing angle, or field of view. Wide gives a bigger field of view, but the objects look smaller in the scene. Tele gives the highest zoom, and gives a narrower field of view. But the objects look bigger in the scene.
[W]WDR (Wide Dynamic Range)
Wide Dynamic Range Technology uses two shutter speeds in alternative video fields-high and normal- every 60th (or 50th) of a second and combines two fields into one progressive scan frame. It allows every detail to be captured accurately even if one portion of an image is bright. Whether at the high shutter speed or normal shutter speed, the progressive scan CCD provides a horizontal resolution of 470 lines. As a result, combined fields yield a frame of high-quality images.
IR means Infrared or infrared radiation. Infrared lies between the visible and unvisible microwave portions of the electromagnetic spectrum. Infrared wavelength is longer than visible and shorter than microwaves. Near-infrared is closer to visible light and far-infrared is closer to microwave region, Mid-infrared is the region between near-infrared and far-infrared. Infrared waves can be measured as the heat an object emits.
[F]Focal Length (f)
The focal length of a lens determines its field of view at a given distance. A wide angle lens as its name suggests a wide field of view at a given distance. This means that it can see a wide area of the scene in both the horizontal and vertical planes. Most lens manufacturers provide tables or charts for their lens providing the necessary data.
f= h x D / H ( h: height of image, D:distance, H: height of Object)
[F]FoV (Field of View)
A FOV refers to the maximum angle over which objects are captured on the sensor in a camera. It depends on two factors - the focal length of the lens and the physical size of the sensor. Sometimes, a FOV is called angle of view.
The FOV of a rectilinear lens is calculated using simple trigonometry as following equation.
FOV = 2 x arctan(frame size/(forcal length * 2))
Here, 'frame size' represents the size of the sensor in the direction measured.