The Hoya R1 Pro Red Filter (often listed as the 25A Red) is a powerful, high-contrast multi-coated filter built primarily for dramatic black-and-white landscape and architectural photography.

• Extreme Contrast Enhancement: Strongly absorbs blue and green light while passing red, orange, and yellow. This turns pale blue skies into near-black backgrounds, making white clouds pop intensely.
• Infrared Capability: Excellent for infrared-sensitive films, cutting through fog and haze while turning green foliage a stark, snowy white.

• HMC Multi-Coating: Features a 6-layer coating (3 layers per side) that achieves over 97% light transmission while suppressing ghosting and lens flare.
• Filter Factor: Has a heavy filter factor of 8, requiring an exposure adjustment of 3 f-stops to compensate for the light blocked by the deep red glass.