UV Blocking Glass Solutions for Color Correction & Scattered UV Elimination in Photography 04/11
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Application Note: UV Blocking Glass Solutions for Color Correction & Scattered UV Elimination in Photography 04/11 When dealing with any kind of photography, you are always dealing with light of some form or an- other. Photography by definition is the act of capturing an image on film or digitally through a lens or an aperture. Modern photography has become so precise and so amazingly beautiful that stunning images have really become the norm. However one of the challenges that photographers have still not been able to completely eliminate with technology, no matter how expensive the camera, is the effect of light that does not fall within the visible spectrum. Ultraviolet light is a significant factor when dealing with unfiltered light. While our eyes cannot see it, the camera does. What we refer to as visible light is light radiation that falls between 400 nm and 700 nm. When you look at a rainbow you can see the spectrum of visible light where the shorter wavelengths of light closer to 400 nm are blue and the longer wavelengths of light closer to 700 nm are red. When you look at the red and blue edges of a rainbow, you should notice that the color seems to fade a bit the farther out you go. This is not because the light isn’t there, it’s because your eyes aren’t capable of seeing those wavelengths. Color film photography presents an interesting problem when it comes to UV light. Color film essen- tially has three color sensitive layers, one of which is blue. The blue layer responds to blue light, but it also responds to UV light. When taking color film photographs in an area with unfiltered light, out- doors for instance, then you run the risk of overexposing the blue layer and ending up with photo- graphs that have a distinctive blue tinge. Our eyes and brains tend to be trained not to see this blue tinge when we are used to seeing it, but then you see a photograph that doesn’t have it and it’s like seeing the world through new eyes. Using a UV blocking glass while taking color film photographs will drastically reduce the blue tinge effect. Digital Photography doesn’t really have the same problem that color film photography has, and while that is good news for digital camera users, there are still other problems to be resolved. One such problem is called “scatter”. This effect is most noticeable when photographing distant subjects and shows up as a bluish haze that reduces the crisp clarity often sought when photographing subjects like mountain ranges or cityscapes. Another difficulty with digital photography in relation to UV is “purple fringing” or PF. This most commonly occurs when a dark subject is backlit on a bright back- ground, such as tree leaves against a clear sky. UV blocking glass filters also help to alleviate this problem. There are other ways to alleviate all of these problems, either through photo manipulation after the fact, or by limiting your choices of subject matter to studio scenes where the light can be filtered at the source. In all of these alternatives, you are limiting the quality and choice of subject matter and not truly solving the problem of ultraviolet light filtering. The best pictures are taken with equipment that solves the problem up front so that quality of the photograph is not adversely affected in devel- opment or touch up. 200 South Hallock Drive, Santa Paula, CA 93060 • (805) 525-4902 • FAX (805) 525-8604 • www.abrisatechnologies.com .