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curtain shutter

noun Photography.
  1. a focal-plane shutter consisting of a curtain on two rollers, moved at a constant speed past the lens opening so as to expose the film to one of several slots in the curtain, the width of which determines the length of exposure.
Also called roller-blind shutter.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018