FILTERS

A filter is a camera accessory consisting of an optical filters that can be inserted in the optical path. The filter can be a square optical glass mounted on a holder accessory; or (more commonly) a glass or plastic disk with a metal or plastic ring frame, which can be screwed in front of the lens.

Filters are commonly used in black and white photography to manipulate image contrast. For example a yellow filter will enhance the contrast between clouds and sky by darkening the latter. Orange and red filters will have a stronger effect. It is also used for color correction and special effect such as sephia.

Filters are less common in color photography (and even less in digital photography). A major use is to compensate the effects of lighting not balanced for the film stock's rated color temperature (usually 3200K for professional tungsten lights and 5500K for daylight): e.g., the 80A blue filter used with daylight film corrects the orange/reddish cast of household tungsten lighting, while the 85 used with tungsten film will correct the bluish cast of daylight.

Nowadays, filters are not popular among the photographer because they can use filter when editing images using software like Adobe Photoshop.

POLARIZER FILTERS

The polarizing filter is one of the most useful filters for outdoor photography. This is the first one you should buy to improve your landscape photography. First of all it can darken blue skies turning them a deep, rich blue. Polarizing filters are also great for removing reflections in water. So if you're shooting a river scene and you want to see detail in the water or on the river bottom, a polarizer will reduce the reflections. They're also good with foliage, making leaves and such less shiny (again, cutting down on reflections). Color saturation is enhanced with almost any subject. No other filter can provide this.

The polarizing filter one thing and one thing well - it removes reflections from non-metallic surfaces:

• Skies- By eliminating the reflection of light on the tiny water droplets present in the atmosphere the polarizer brings more saturated and slightly darker skies.

• Water and reflective surfaces-By eliminating reflections, the polarizing filter will tend to make water and other reflective surfaces more transparent. The effect will also vary depending on the angle to the reflective surface. If you place your camera very low above a river, the effect will be very limited. If you shoot from a bridge above it, the water will look totally transparent.

• Color Enhancement-The polarizing filter also reduces reflection from other surfaces such as foliage and thus makes their colors look more intense. It also tends to make shadow areas darker.

• Light absorption-The main side-effect of the polarizing filter is that it absorbs 1.5 stop of light. So, if you shoot at 1/180th of a second and then add the filter, you will find yourself at 1/60th of a second. This happens whatever the orientation for a polarizer. In low light situations, some type of camera support, such as a tripod, will be needed.

DL (LINEAR POLARIZING)

A linear polarizer is a device which selectively allows the passage of only certain orientations of plane polarized light. At one orientation it might allow the passage of only vertically polarized light, while if rotated by 90 degrees it would allow the passage of only horizontally polarized light. Half way in between, at say 45 degrees rotation, it would allow passage of only 45 degree plane polarized light.

DL-CIR (CIRCULAR POLARIZER)

A "circular polarizer" actually consists of two elements. The first is a linear polarizer, exactly the same thing as the linear polarizer we have just discussed. The second. element is called a quarter wave plate and it is cemented to the back of the linear polarizer with a specific orientation such that the light emerging from the quarter wave plate is circularly polarized (hence the "circular" polarizer name)

EXAMPLES (IMAGES THAT USED FILTERS):