The light detectors in telescopes record light in a linear fashion. That means that if the light is twice as bright it will appear as twice as bright in the detector. This is not how light is detected in our eyes. Light detection in our eyes is recorded in a logarithmic way. If a light appears to be 5 times as bright it is in fact 100 times as bright. This allows us to visualize a large variety of brightness in objects.
(The Great Courses – The Life and Death of Stars)