Wavelength range 380–750 nm that human eyes perceive — violet to red. Cameras sense IR and UV differently, which matters for color grading and sensor response.
The range perceived by your eye lies between 380 and 750 nanometers—from deep violet to the red end. Everything below this (ultraviolet) and above it (infrared) does not exist for your visual perception. This is the crucial problem on set: your camera sometimes sees differently than you do, and this can lead to surprises during rushes.
In practical use, you'll immediately notice this with sensors that have aggressive infrared filtering or lack it entirely. Cheap cameras or older chips often have weak IR cuts, meaning they pick up heat radiation from lamps and reflectors that your eye perceives as neutral white. The camera interprets this as a pinkish color cast, especially in the highlights. Conversely, modern digital sensors are often hypersensitive in the near-infrared—which is why you need to white balance even more aggressively with a Color Checker than you did with film. The color you see is not the color the sensor captures.
The visible spectrum itself is mapped by three color channels (red, green, blue), but not linearly—your eye perceives green more strongly, which is why digital cameras have two green photodiodes per red and blue (Bayer pattern). This isn't necessarily wrong, but it explains why green screens work better than red ones, and why skin tones are more critical in green. When working with strong blue or red practical lights, you quickly reach the limit of what the sensor can differentiate—the dynamic range shrinks dramatically in these areas.
In practice, this means: pay attention to the spectral distribution of your light sources, not just their color temperature in Kelvin. LED panels with a poor CRI (Color Rendering Index) have peaks and gaps in the visible spectrum that your eye integrates but the sensor captures individually. This creates metameric failures—two lights that look identical to you produce completely different colors on camera. The solution: always check with a spectrometer, not just with the naked eye.