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the black background (in most of the pics) by the way is a piece of what they call 'theatre blackout' cloth. They use for events to cover up seats that are empty and don't want you know they are empty
Zero light reflectivity and zero light gets thru it...totally black out. If its not cloth using the flash set at around -1 compensation then get far enough back from the flash that you don't get artifacts or reflections off glass shiny doors etc etc will give you a nice black background with no cloth.
They left behind a few whole rolls of the cloth and I have enough to cover a small island like Cristo