The Hoya 25A red filter is especially effective for increasing contrast in black & white photography. Ideal for dramatic cloud effects in landscapes, due to it’s blocking of the color blue rendering those areas of the sky darker. It can also be applied creatively in color and infrared photography. The 25A blocks over 90% of the light below 650mn, transmitting only red. For Color Photography: While this filter was designed for black & white photography, it can be used with color film to produce a specific color effect. 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. Filter Factor: 2.5 stops Glass Type: Hoya Optical Number of Multi-Coatings: 6 Layers / 3 per side Hardened Top Layer: No Anti-Static: No Frame Construction: Standard Profile / Aluminum Front Filter Threads: Yes