Marshall wrote:Magnesium doesn't change in brightness according to how much there is, it's pretty much just the same light being produced
Not at all, thats like saying if the sun was half its size it would be the same brightness.
A meter of magnesium WILL temporarily blind you if you even glimpse at it, the light is so bright and concentrated it "burns" light on to your retinas (same effect as staring at the sun, or a light bulb for a few seconds). Staring at a magnesium strip burning for a few seconds is enough to render you partially blind for a few days, and any longer could possibly blind you permanently.