@leah @nCrazed @f4grx @FabMusacchio You are right if the image is itself a parallel projection, but the images from cameras are perspectives, where parallel rays/lines in 3d always converge somewhere (except rays/lines parallel to the sensor).

@nCrazed @leah @f4grx @FabMusacchio Sunrays are quasi-parallel in the 3rd dimension, however they all diverge from the sun when projected on a surface such as a camera sensor or our retina. What difference does it make if the trick works with lamps too ? The sun is just a big, faraway lamp, and the rules of convergence in 2d spaces apply just the same for all 1d-ish lightsources.

The trick works if you don't mind for lens distortion, which are really minor on most smartphone cameras nowadays (do not mess lens distortion with surface distortion caused by planar projection on sensors, the latter doesn't affect convergence even though it can exxagerate surfaces on the sides of the pic).