Filters give the photographer more latitude in creating a digital photo.
Photographers using film cameras typically rely on filters to manipulate spectral content and light quality. Color functions can, to a point, be managed in-camera by digital photographers by manipulating the data with white balance and effects functions. Dealing with uncompromising light, however, is still best left to an array of specialized filters that block or filter portions of the light entering the camera.
Polarizing Filters
Polarizers combat white outs (excessively bright areas of an image) that bounce off glass, water, metal and even foliage, by reducing the contrast in these areas. They also deepen the color saturation, giving a more natural look that is difficult to replicate in post.
Ultraviolet Filters
UV filters are less common because the effect of "UV scattering" is minimal at low altitudes. They block the most of the UV B and UV C light ranges, which can --- particularly at altitudes above 10,000 feet --- scatter in the image, causing foggy backgrounds and a slightly blue cast to daylight images.
Infrared Filters
Infrared light is invisible to the naked eye, so digital cameras are equipped with an onboard IR filter to reduce the unwanted influence of IR on the image. Not all of the IR light is blocked, however, so to capture an image in IR, a filter is used to block the visible light. The tiny amount of IR that sneaks past the onboard filter (provided the photographer uses a very slow shutter and wide aperture) creates a haunting, high-contrast image that, for example, would render the sky black and foliage white.
Neutral Density
Neutral Density filters are light blocks that reduce the amount of light hitting the camera sensor. This allows a photographer to use slower shutter speeds or wider apertures to shoot the picture. The filters are termed "neutral" because they block all light evenly without changing the color characteristics or polarization. ND filters are graded by the amount of light they reduce, which is quantified as a number of stops on the F-scale (degree of aperture).
Special Effects
Effects filters generally save time in post-processing by creating the desired effect in the captured image. Some examples include soft filters, fog, star and cross-screen filters. These are generally used for creative options, but many of the captured effects can also be achieved in post-production (with image editing software) if the photographer so chooses.
Colors
While the onboard menus in digital cameras offer a wide array of color functions, and post-processing programs can manipulate color to the photographer's liking, color filters are still sometimes used to create an overall effect. They are especially helpful to add contrast when the final image will be converted to black and white.
Tags: amount light, digital cameras, image that, Neutral Density, onboard filter
