EM window:

To obtain some idea of what a small EM "window" is symbolized by the visible-light wavelengths, attempt looking through a red- or blue-colored piece of glass or cellophane. Such a color filter very much limits the view you acquire of the world since only a narrow variety of visible wavelengths can pass via it. Various colors cannot be ascertained via the filter. For illustration, whenever a scene is viewed via a red filter, the whole thing is a shade of red or almost red. Blue emerges similar as black, bright red emerges similar as white, and maroon red emerges similar as gray. The other colors appear red with changeable degrees of saturation, though there is little or no variation in the hue. When our eyes had built-in red color filters, we would be fairly much color-blind.

Whenever considered with respect to the whole EM spectrum, all optical instruments suffer from similar kind of handicap we would have when the lenses in our eyeballs were tinted red. The variety of wavelengths we can detect with our eyes is around 770 nm at the highest and 390 nm at the lowest. Energy at the highest visible wavelengths emerges red to our eyes, and energy at the lowest visible wavelengths emerges violet. The intervening wavelengths illustrate up as yellow, orange, green, blue, & indigo.