A darkroom contains a first film unwinding unit which receives reels with convoluted undeveloped customer films from a device serving to remove reels from their cassettes. Each film which is being unwound from its reel is normally advanced in a first channel to a splicer which connects its leader to the trailing end of the preceding film to form a long web which is collected into a large roll prior to transfer into a developing machine. A second unwinding unit in the darkroom can receive reels with damaged films from the first unit or from another source of undeveloped films and has a receptacle for reels. A second channel extends from an outlet of the receptacle to a portion of the first channel ahead of the splicer. The two units can be reached by hands which must extend through contractible openings of two cuffs and thereupon through a contractible opening between several curtains of the darkroom. This enables an operator to transfer individual reels from the first unit into the receptacle of the second unit and to initiate the advancement of film into and through the second channel and severing of film in the second channel.