• Skylight filters make a standard zoom lens even more versatile.Lens image by pershing from Fotolia.com
  
  Lens filters are an important tool in digital and film photography. In particular, a skylight filter, also known as a 1A filter, is useful whenever shooting outdoors. While digital cameras may have automatic features that perform many of the same functions as a skylight filter, photographers using color reversal film rely on screw-on skylight filters for a variety of effects that come from removing ultraviolet light.
  
  

Remove UV Light

• One of the primary effects of a skylight filter is to prevent ultraviolet, or UV, light from reaching the film inside the camera. The filter does this by using a series of layers to cancel out the particular wavelength of UV light. While UV light is invisible to the human eye, color reversal film can detect it and may not produce the image that the photographer expects unless it is filtered out.
  
  

Add Warmth

• Skylight filters add warmth to a color image. In the finished photograph, UV light reads as a bluish tint. By removing the blue tint, the image takes on a more natural tone that mimics what the human eye sees. This image may look slightly more orange when compared to an unfiltered image from the same session.
  
  

Reduce Haze

• Skylight filters also have the effect of reducing haze, especially in photographs taken from a great distance. It eliminates the haze effect that occurs when sunlight reflects off particles in the atmosphere between a viewer and a distant subject.
  
  

Increase Sharpness

• Skylight filters also function to increase the overall sharpness of an image. This gives objects more rigidly defined edges and may create a sense of depth as some objects pull into the foreground and others recede into the background.