I took this with my Nikon DSLR about a month ago. Today I was going through the photos and was just about to delete this otherwise unremarkable picture when I noticed a large artifact over the image of my wife's iPhone. It looks like a reflection. Is it coming from the camera, sensor, lens? What do you think?
Looks like a pattern created by the 2D diffraction grating. In the case of a smartphone screen, the individual pixels form the rectangular array, exactly like how the typical 2D grating is built. The effect can be more or less visible depending on the specific screen technology and pixel density.