How to prevent the audience from discovering the camera in film and television works?

A camera is equivalent to a human eye. A camera is a camera that can shoot continuously. Therefore, we can look in the mirror and see where we can't see our eyes. It is easy to explain using physical knowledge. For the convenience of explanation, a picture is drawn below. When the human eye is at point A, according to the imaging characteristics of the plane mirror, the image A' of point A is drawn, passing A' and the edges M and N of the plane mirror. Draw two straight lines A'MC and A'ND, then the part between MC and ND is the range observed by the human eye at point A. In the same way, the range observed by the human eye at point B is the part between ME and NF.

It can be seen that if the plane mirror is fixed and the position of the human eye moves in the direction parallel to the plane mirror, the observable range of the human eye will be opposite to the direction of movement of the human eye. It is not difficult to imagine that if the human eye moves to a certain position, it will not be able to observe its own image. And it is outside the light emitted by the human eye reflected by the edge of the plane mirror.

When the human eye is at the edge, the reflected light coincides with the incident light, including the normal line, that is, "three lines in one". According to the law of light reflection, at this time, the human eye is facing the plane mirror. The edge position, so as long as the human eye is outside the edge position facing the plane mirror, it cannot see itself. When a person stands in front of a plane mirror, the actual observation results are the same.

In this way, when shooting, the camera only needs to be pushed beyond the range facing the edge of the plane mirror to avoid shooting the camera. It could also be that a staff member was erasing the camera in the mirror frame by frame, which was time-consuming and laborious.