Cokin Blue conversion filters supress or greatly subdue the strong orange tones due to tunsten or halogen lighting. They replace the flat uniformity of flashlight photos with an intimate and atmospheric lighting, with sculptured shadows, without altering color tones. Blue conversion filters are also perfect for party lights, shop windows and illuminated monuments. Use dark blue A020 with daylight film under tungsten lights. Use medium blue A021 or light blue A022 with daylight film under halogen light