The cokin p series p027 warm 81b filter is designed to add more warmth to a photograph whilst removing bluish casts from open shades this filter eliminates excessive amounts of blue from the effects of electronic flashes and is stronger than the 81a warming scenes shot on overcast days this product is a light balancing filter which reduces colour temperature slightly for a warmer tone it corrects propensity towards blue tones and alters colour temperature 81 series conversio