What is the physics behind these rays of light visible in the photographs of objects that emit light? What justifies their shape and amount of rays?
Very well known effect in a sense, but I did not find any deep explanation...
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1https://physics.stackexchange.com/questions/35935/what-are-these-rays-that-appear-in-photograph-of-sun and links therein. I think there is also a question about it with very good answers somewhere on [photo.se]. – dmckee --- ex-moderator kitten Aug 19 '19 at 17:43
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1Many camera lenses (including most professional camera lenses) contain an [iris diaphragm](https://en.wikipedia.org/wiki/Diaphragm(optics)#Iris_diaphragms_versus_other_types)_ in the optical path. I don't know the mechanism--maybe diffraction, because the edges of the diaphragm blades are very sharp--but the number of points on the "stars" that you see around each bright light source will be 2x the number of blades in the diaphragm if that number is odd, or 1x if the number is even. – Solomon Slow Aug 19 '19 at 20:59