The focal length of the USB camera lens refers to the distance from the lens center to the imaging sensor. The focal length represents the viewing angle. Generally speaking, the smaller the focal length, the larger the angle. The larger the focal length, the closer the distant scenery can be, so that the main body can be imaged on the screen, showing details, but the angle of view is small; The focal length is large and the depth of field is shallow, which can virtualize the background; The smaller the focal length, the more scenery can be accommodated, and the wider the angle of view, which is suitable for taking larger scenes or landscapes; The focal length is small and the depth of field is large, so you can shoot the distant and near scenery clearly; Generally speaking, the aperture at the wide-angle end is larger and the aperture at the long focal end is smaller.
So how to choose the focal length and how much is appropriate for choosing a home camera?
Choose according to the scene. If the bedroom is not large, you can choose a common one, such as the one with 8mm focal length, which is suitable for the bedroom, study and baby room. The camera angle is generally about 90°, with a flat angle lens.
For a wide range of cameras, such as the living room, a camera with a large wide angle of 160° or a pan tilt rotation can be selected to ensure that the viewing angle is sufficient to monitor all corners.
