ISO myths and reality strong er signals

■ When we talk about raising or lowering the ISO, you’d be forgiven for thinking that the sensitivity is being changed. It isn’t. The sensor has a fixed sensitivity, meaning a fixed response to the light striking it, and with Nikon constantly improving sensor performance, it’s as good as you can get. What happens when you raise the ISO is that the signal from the sensor is amplified in the camera. That, simply, is why increasing the ISO creates a noisier image, because amplifying the signal also means amplifying the noise from the camera electronics.