FMS - The Fluorescent Mineral Society

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Note the short shutter speed of 1/16 sec in the Exif details. The orange manganese phosphorescence lasts longer than this, but the shorter exposure causes the green willemite phosphorescence to appear relatively weak compared to the longer 2 second exposure. Both colors exhibit an exponential decay, but the orange starts much brighter while the weaker green lasts much longer. Opening the shutter 1/4 second after the flash would reveal mainly green phosphorescence.