UV Filter The ultraviolet (UV) filter prevents UV light from reaching the lens, helping increase clarity and reduce haze. As a result, your photos look crystal clear even in mountainous and coastal areas, where ultraviolet light is particularly strong. CPL Filter The circular polarizer filter (CPL), meanwhile, is essential for outdoor photography, as it deepens the intensity of blue skies and reduces or eliminates glare. (Note that the circular polarizer is designed expressly for autofocus cameras.) Polarizers provide color and contrast enhancement. Reflected light often shows up as whitish glare that washes out color in an image. A Polarizer corrects this problem producing deep, dramatically blue skies. It also removes glare from non-metallic surfaces, such as windows and water. Color saturation in general, especially outdoors, can be improved significantly. Think of it as sunglasses for your camera. FLD Filter Finally, the kit offers an FLD filter which helps balance light in outdoor situations. FLD Filter provides correct color, removing harsh green cast caused by fluorescent bulbs. The FL-D and can help create pleasing skin tones under fluorescent lighting without a flash and true-to-life color rendition, along with being an essential tool in any environment where the ambient light is fluorescent.