Peter, that comment helped to clarify something that I've wondered about for some time. I remember seeing the aurorae "above" Lake Michigan one winter evening, looking north from Evanston (Chicago), around 1986. It was intense and weird, but looked white or yellowish-beige-white. Nothing like the green or reddish hues often depicted. So the reason is quantum efficiency...
Thanks, Eric! The human eye loses color vision in dim light (the monochrome 'rods' are more sensitive than the color 'cones'). To the naked eye, these aurorae looked more white (or gray) than green. But the time exposure in the camera brought out the real color. I know there can be much brighter shows after solar storms -- I've seen some fantastic galleries here on PBase.
I have GOT to see this in person. Don't you mean the colors are more intense than can be captured by a camera? Pretty steady shot for 2s handheld on a boat.