Orange filters such as the Hoya G are used mainly, but not exclusively, for black-and-white photography. They lightens reds, oranges and yellows, darken blues and greens, and increase contrast between reds and yellows. Orange filters were once known by photographers as furniture filters because they lightened the tone of wood, making the dark areas of grain stand out. For similar reasons they also enhance the surface textures of brick and stonework. They help to penetrate heavy haze, and are consequently effective for distant landscapes and other outdoor telephoto work. They also render blue skies almost black, and subdue skin blemishes and freckles.