Digital Photography Classes is continuation of Taking a photography ( Special lenses )
Please see my previous post about Photography Classes, Digital Photography Schools, below here :
Macro lenses are designed for use a distances close enough to produce very large images, image size equal to object size. The original macro lenses were use on long bellows or extension tubes, many modern macro lenses cameras have extension tubes built to permit focusing very close up.
Lens Extenders fir between a lens and the camera body to provide a increase in expensive than telephoto lenss, they reduce the speed of the lens at all stops, and exposures must be increased accordingly.
Zoom and varifocal lenses can be many of a continuous range of focal length providing photographer with the picture taking capabilities of several lenses.
Filters. A filter placed in front of the lens changes the color of light. although not essential, correction filters provide the most accurate translation of subject colors into shades of gray on panchromatic. Color conversion and light balancing filters for color photography change the overall color balance of light. While a great deal of photography uses existing light with great success, it is often necessary to add light to a scene for proper exposure or a different lighting effect. Photographic light sources include incandescent and tungstenhalogen lamps, flashbulbs, and electronic flash tubes.
In controlling lighting contrast, the photographer generally uses more than one source of light. Usually he begins by placing the main light on the subject, and then he addssufficient fill supplementary light to raise the shadows and dark areas to a suitable brightness. To avoid excessive contrast in outdoor portraits on sunny days, the use of the sun as the key light and flash as the fill is effective. Another good way to avoid excessive contrast especially in color photography is to place the subject of the picture in open shade that is, an area lighted by the bright sky but not by direct sunlight.