The first step in unraveling the great mystery of what IR filters do, why you need one, and which one do you chose, has to start with an explanation of What IR is. Infrared light is a part of the electromagnetic spectrum just bellow what we call visible light. Visible light is a very narrow part of the electromagnetic spectrum that the human eye is sensitive to and allows us to see. This is measured in wavelength between 390-700 nm (nanometers). Essentially the longer the wave the warmer the light. Reds being in the bottom of that range and blues and violets at the top and a shorter wavelength. Infrared is actually split into three ranges described by their distance from the visible range. Continue reading
After seeing what Arri put out on their Facebook page the other day, I wanted to try to achieve something similar. For my test I used an Alexa Plus 4:3 with a Zeiss Master Prime at T1.3, and an EK87 Infrared filter. The Camera was set to 3200iso, 5600° kelvin, 358° shutter.