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Credit: ESA–V. Crobu
Cave photography is both a science and an art! Usually a lens exposure of around 30 seconds is used to give enough time for multiple flashes to light up different areas of the cave in order to get the correct illumination. It doesn't have to be a flash, sometime helmet lights or flashlights can be used but then the white balance has to be adjusted for the different frequencies of 'white' light that is used. This photo was taken on September 4, 2012.