When David Hay shot on film, there was never much concern about diffraction causing image quality loss. So, why is diffraction such a hot topic in the digital era? You should be aware of it, but not frightened by it
First of all, what is diffraction? When light passes through a large aperture, such as f/2, most of that light passes straight through the centre of the lens and onto the sensor. However, if you set a small aperture, such as f/22, all of the light has to squeeze through a much smaller hole and some of it scrapes past the edges of the blades of the diaphragm. This causes some of the light to be deflected and each point of light is then surrounded by a halo.
If you are photographing a sunset, think of each point of light as being a bit like a…
Read this and many more articles in High Definition inside Issue 39 of Landscape Photography Magazine.