If you see the camera, the camera sees you.

Today there was a group shot in the institute. All staff including the students were invited to meet up along the stair of a certain building, yet everyone on the floor of his/her study room or laboratory. It was exciting seeing many people by turning your neck around, up, and down. We were supposed to look at a camera held by a photographer on the uppermost floor, you can imagine everyone looking at the photographer, and no clue if she or he was seen by the camera. Later a professor said, "My theory is that if you see the camera, the camera sees you, maybe." So I wonder if he is right.
It is clear if you are out of the frame, you are not captured, even if you can see the camera. Whether you are in or out, and in what size you appear in the photo depend on the focal length. The focal length f is the distance of the pinhole from the image. If the size of an object is S and it is located in the distance D of the camera, the size of the image will be s = S * f / D.
The focal length can be adjusted using a zoom lens mounted on a camera. Bigger focal length, greater magnification, thus the objects appear closer, yet the narrower field of the view is captured. If we decrease the focal length, objects appear smaller and further away, however wider field of the view is captured by the camera.
So the photographer today perhaps decreased the focal length such that people on the zeroth floor also appear on the photo, thus we will all look tiny tiny, considering 7 floors in the institute. Anyway let's wait to see if the photographer put us in the frame.