W2 color correction filter warms the ambient light entering the lens by 200° kelvin (+20 mired shift) by adding light amber color to the overall exposure. This filter helps fine-tune the color or look of your scene to match your film's white balance or creative vision. The Hoya W2 filter is helpful when: You are using daylight-balanced film and the light source is cooler than the desired look and you need a specific amount of color correction to match your film's color balance (5500°K). Great on light overcast days or when you subject is in the shade. When shooting portraits and you want to give the skin tone a warm look. You are shooting at sunrise or sunset with daylight-balanced film (5500° K) and you want to enhance the warmth of the scene. HOYA Multi-Coat (HMC) filters are recommended for enhancing the performance of today's multicoated lenses. These popular filters minimize reflection, reduce flare and ghosting, and result in over 97% average light transmission.