The Hoya Warm filter has a more reddish color balance than an 81A or an 81B. It reduces colors in the blue to blue-green area of the spectrum, making skins tones seem more healthy, glowing and slightly suntanned. This filter was designed for fashion photography and outdoor portraiture. It is available in both standard and Hoya multicoated to greatly reduce the risk of flare and ghosting. The Hoya WARM and WARM HMC are available in filter sizes 49mm through 77mm. Filter Factor: 1.4 F-Stop Compensation: 1/2 stop