Diffraction and digital photography
(Monday, July 21st, 2008)
Several times, I talked about the limitation to photo image quality by light diffraction but I failed to go into the details. To the general request of one reader who asked, I will try to give some explanations to better understand why the digital photographer must absolutely take that into account to make better pictures and to choose its camera.
The first thing to know is that light diffraction is a very general phenomenon and quite natural. It’s been a long time already that scientists and engineers noticed that -on the one hand- light rays are slightly deflected while running through a very small orifice and -on the other hand- two light rays can interact with each other on the condition that they are have very paths nearly perfectly parallel. This is even one of the most significant and founding elements of quantum physics. When you combine both those phenomenons, you will notice that light going through a very small opening like camera lens diaphragm will produce not exactly the expected neat circle but a more irregular and circular shape that you can see in the illustrative figure that goes along this paragraph: Usually named an Airy disk or Airy disc.
