INFRARED
PHOTOGRAPHY WITH DIGITAL CAMERAS
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Three
Filters
There are two types of filters used for infrared photography: "see through" (red) and "opaque" (seemingly black). They are further categorized by number according to their increasingly surreal effect illustrated above.
The see-through ("false") filters, #25, #29, and #70, filter out some of the visible light but allow enough "visible light" through to focus. The "opaque" ("True") filters, #18A, #89B, #88A, #87, #87C, #87B, #87A, cut down so much of the "visible" light that you'll need a tripod and must pre-focus before putting the filter on. Focusing your camera with the "true infrared filters" and ensuring good depth of field is not as much of an issue with digital cameras because the small CCD allows for much greater focusing latitude.
The see-through red filters produce interesting color and black- and-white effects and can be used for action photography. This is because they allow some of the visible spectrum into the image, which makes for dramatic color effects when you adjust them in Photoshop.
The opaque or "true" infrared filters are better suited for black- and-white imaging, but far more subtle effects can be obtained in color. You will need a tripod to use the opaque filters as you must focus before you put the filter on, and the shutter speeds are typically very slow. The opaque filters cut out the visible light where the visible and invisible spectrum overlap, resulting in long exposures.
True Color versus False Color
There's a great deal of controversy about "true" versus "false" color in the infrared photographic community. In fact, there is no such thing as "true" or "false" color since we are making "invisible light" visible, and so anything we produce in color or black and white is an interpolation.
You can't hear the high-pitched whistle that a dog hears, nor can it be described. It can, however, be recorded and interpolated, so that we have an idea of what the dog is reacting to. Such is the case with infrared film. We can only guess what the infrared spectrum looks like, and any images we get out of the process may indeed be "true or false." In the end, it's not a matter of true or false, but whether or not the use of infrared actually enhances the image.
