I thought this would be a useless accessory until I read in the user manual: "[When taking photos without your eye to the viewfinder, remove the DK-20 rubber eyecup and insert this DK-5 eyepiece cap to prevent light entering via the viewfinder interfering with exposure.]"--- If you switch to live view I think DK-5 has no function because the mirror in the camera flips and blocks out light from the eyepiece anyway.