HOYA 55mm YELLOW K2 PHOTOGRAPHIC LENS FILTER: Electronics. Adds mild contrast to all daylight exposures. 。 Most natural tonal effect. 。 Offsets excess coolness of flash portraits. 。 Yellow is the mildest of the contrast filters for black and white photography. Yellow filters produce the most natural tonal range. By absorbing ultra-violet, violet and blue it moderately increases contrast in sky, foliage and architecture photography. It's natural tone reproduction in landscapes, cityscapes and portraits make very it useful for all daylight exposures. Available in most sizes. 。 。 。