23a02ApparentDepth.pdf (10.1 MB)
Location of the virtual image for an underwater object observed at oblique angles
preprintposted on 2023-10-03, 10:02 authored by Tohei Moritani
When observed with a telephoto camera at oblique angles, a reflected light spot on a steel ball in the water has been found to give two focused linear images, one vertical and the other horizontal, at different foci: the former is located just above the object and the latter closer to the camera. The camera’s manual focus ring has determined their locations. A steel ball has been used as a “guide” to determine the locations of ordinary objects that are too blurry to focus on under the same conditions. A regular camera captures the complete overlap of the two images for the ordinary object. The human eye perceives the image just above the object due to the psychological familiarity cue.