Hoya 52mm Red #25 Glass Filter
The most popular of the contrast filters for black and white photography, Red creates dramatic effects by brightening red and orange while darkening blue and blue-green in sky, water and architectural scenes.
With underexposure, the red filter may be used to simulate a moonlit scene at midday.
With infrared film, the filter gives extreme contrast to skies, turning foliage white and cutting through fog and haze.
Red filters are available in most sizes.