What’s the ISO of an eye? It ranges between 25 and 60,000.
Absolute versus subjective measuring of light: Simply speaking, the human eye is asubjective device. This means that your eyes work in harmony with your brain to create the images you perceive: Your eyes are adjusting the focus (by bending the light through the lens in your eyeballs) and translating photons (light) into an electrical impulse your brain can process. From there onwards, it’s all about your brain: It is continuously readjusting its colour balance according to the lighting context. In other words, our eyes know what must be seen as red or white or black etc.
A camera, on the other hand, is an absolute measurement device – It is measuring the light that hits a series of sensor, but the sensor is ‘dumb’, and the signals recorded need to be adjusted to suit the color temperature of the light illuminating the scene, for example