■ This filter corrects the bluish cast that appears in shadows or on cloudy days, rendering natural colors. ■ When shooting with color reversal film, there is no "white balance" function like in digital cameras, so color adjustment is necessary with filters. MC W4 is a filter that removes the blue cast under cloudy skies. ※ I purchased this a long time ago and haven't used it much, so it has been stored at home. Therefore, it shows some signs of use, so please refrain from purchasing if you are sensitive to this. m(_ _)m