Wednesday, March 31, 2010

Filters 101

A filters function is to absorb certain light and allow other light to pass through either partially or completely. They are generally made of glass, plastic, or sheets of gelatin. Different filters allow the photographer to express individual creativity and aid in correcting any undesirable components. Each filter alters light in different ways; they can be used alone or in combination with one another to achieve seemingly infinite results.

The most basic filters provide little more than protection for your lens. Lenses can be a costly investment, and a good protective filter will easily shield a lens from devastating damage. Replacing a filter is a lot easier to endure than replacing a lens.

  • MC protective filters are clear filters designed to protect the lens without affecting the light that passes through it. Use of these filters with show no effect on the final image. These filters are usually left on the end of the lens and won’t affect the performance of other filters used in combination with it.
  • UV filters are also a first choice for protecting a lens. These filters absorb UV light that often appears as a bluish tone in photographs. Common practice is to keep these filters on the lens at all times as the effect is minimal and often desired. UV filters are increasingly effective at higher altitudes, over long distances, and above water. In hazier conditions, stronger UV Haze filters will have a more dramatic effect, sometimes resulting in a yellow tone. Although it is not possible to filter out dust and fog, UV Haze filters will filter out the UV light reflecting off of them.
  • Sky filters are chromatic (colored) filters, usually a light shade of pink or magenta. They also help reduce the effect caused by UV light, and add warmth to the photograph. When photographing people, Sky filters can be used to help prevent the light reflecting off of nearby objects from disturbing skin tones.
  • Neutral Density filters are designed to reduce brightness without sacrificing color. These filters are useful when shooting in bright conditions where fast shutter speeds still result in over exposure. Longer exposure times allow for creative effects, such as softening moving water, and give a lot of freedom to the photographer for experimentation. Reducing the brightness of light also allows for wider aperture settings, which will reduce the depth of field.
  • Polarizer filters are generally used to reduce and eliminate reflections on non-metal surfaces. Depending on the angle, reflections on water and glass can be eliminated, allowing you to focus on subjects within. Polarized filters can also be used to darken the sky, and increase contrast and saturation. A common practice is to point at the sun with your hand in the form of a pistol. The part of the sky that your thumb is pointing at is where the darkening effect with be more intense. Circular polarized filters allow you to rotate the filter, changing the intensity of the filter’s effect.
Above: No Filter, SOOC
Above: With Polarizer Filter
Left: No Filter, Right: Polarizer Filter

~Andy McCarrick