Question

I happened upon this video purportedly showing a coin on a horizontal table receding away from a lens would disappear from bottom up. The explanation via diffraction resolution limit is wrong. However, I would like to find the correct explanation of the phenomenon.

When the camera zooms in and focuses on the coin, the coin appears clearly. This can be explain by the fact that part of the light from the coin still enters the aperture of the lens. However, how would one explain the abrupt disappearance of the bottom of the coin below the table upper edge when the focus of the lens is on the table edge?
Options:
A) Diffraction due to the resolution limit of the lens distorts the image, causing the bottom of the coin to vanish.
B) Refraction effects of the lens alter the light path, resulting in the bottom of the coin disappearing as it moves away from the lens.
C) The abrupt disappearance occurs due to the change in the lens's focal point and the alignment with the table edge, obstructing the view of the bottom of the coin.
D) The phenomenon is an optical illusion caused by the specific angle at which the camera captures the coin relative to the table edge.

Answer 1

The abrupt disappearance of the bottom of the coin below the table edge is due to the change in the lens's focal point and the alignment with the table edge.

Step-by-step explanation:

The correct explanation for the phenomenon of the bottom of the coin disappearing when the focus of the lens is on the table edge is option C) The abrupt disappearance occurs due to the change in the lens's focal point and the alignment with the table edge, obstructing the view of the bottom of the coin.

When the lens is focused on the table edge, the bottom of the coin is outside the lens's focal point. This means that the light rays coming from the bottom of the coin are not properly focused onto the camera sensor, causing the bottom of the coin to appear blurred or disappear.

This is similar to when you try to focus a camera on a subject that is too close or too far away, causing parts of the image to be out of focus.