Sunday, June 29, 2008

Macro Photography

This Photo is one of sample makro photography that taken from Profesional Digital Camera :

Macro Photography is close-up photography. the classical definition is that the image projected on the film plane is close to the same size as the subject. Many 35mm macro lenses are 1:1, meaning the image on the film is the same size as the object being photographed. Another important distinction is that lenses designed for macro are usually at their sharpest at macro focus distances and are not quite as sharp at other focus distances.

In recent years, the term macro has been used in marketing material to mean being able to focus on a subject close enough so that when a regular 6×4 inch (15×10 cm) print is made, the image is life-size or larger. This requires a magnification ratio of only approximately 1:4, more easily attainable by lens makers.

In the digital world, true macro photography is possible only with single-lens reflex cameras that take interchangeable lenses, such as the Canon D30, the Fuji S1, the Nikon D1, and the various Kodak professional bodies. One nice thing about these cameras is that their small CCDs effectively magnify the image captured by whatever macro lens you've purchased. Thus a 100mm macro lens mounted on a Canon D30 effectively becomes a 160mm lens. And if the lens gives 1:1 magnification on 35mm film, you get 1.6:1 on the D30's sensor.
Doing it all with a 50mm Normal Len

Equipment for making the image the required size includes:

  • Macro photography is Using a special-purpose lens called a macro lens, having a long barrel for close focusing. A macro lens might be optimized to provide its best performance at a magnification of 1:1. Some macro lenses, like the Canon MP-E 65mm f/2.8 can achieve even better magnification— up to 5:1 macro, bringing the structure of small insect eyes, snowflakes, and other minuscule but detailed objects into striking focus. However, it is more common for a photographer to use a "standard" (1:1) macro lens. There are different categories of macro lenses, depending on the focal length:
    • 50–60mm range typically used for product photography and small objects
    • 90–105mm range the standard focal range used for insects, flowers, small objects
    • 150–200mm range gives more working distance — typically used for insects and small animals
    • a few zooms provide a macro option, but they generally do not allow a 1:1 magnification
  • Placing an extension tube between the camera body and the lens. The tube has no glass in it; its sole purpose is to move the lens farther from the film or digital sensor. The farther the lens is from the film or sensor, the closer the focusing distance (and the greater the magnification) and the darker the image. Tubes of various lengths can be stacked together, allowing for increasing levels of magnification while simultaneously decreasing working distance. With tubes attached, the camera will often lose the ability to focus to infinity.
  • Using a bellows attachment between the camera body and the lens to extend the lens to film plane distance. Similar to an extension tube, but adjustable.
  • Placing an auxiliary close up lens in front of the camera's taking lens. Inexpensive screw-in or slip-on attachments provide close focusing at very low cost. The quality is variable, with some two-element versions being excellent while many inexpensive single element lenses exhibit chromatic abberation and reduced sharpness of the resulting image. This method works with cameras that have built-in lenses. These lenses add diopters to the optical power of the lens, decreasing the minimum focusing distance, and allowing the camera to get closer to the subject.
  • Attaching a telephoto extender between the camera body and the lens. A 1.4× or 2× teleconverter gives a larger image, adding macro capabilities. As with an extension tube, less light will reach the film or sensor, and a longer exposure time will be needed. However, working distance remains the same as without the teleconverter.
  • Reversing the lens using a "reversing ring". This special adapter attaches to the filter thread on the front of a lens and makes it possible to attach the lens in reverse. Excellent quality results up to 4x lifesize magnification using fairly cheap, "standard" (not specially designed for macro) lenses can be produced. For cameras with all-electronic communications between the lens and the camera body, such as Canon EOS, reversing rings are available which allow all camera functions, including open aperture metering, to be used. When used with extension tubes or bellows a relatively cheap but highly versatile macro system can be assembled.
  • Reversing a lens of lesser focal length in front of a normally mounted lens using a very inexpensive "macro coupler," which uses two male filter threads to join lenses. This method allows most cameras to maintain the full function of electronic communication with the normally mounted lens for features such as open-aperture metering. Magnification ratio is calculated by dividing the focal length of the normally mounted lens by the focal length of the reversed lens (i.e., when a 18 mm lens is reverse mounted on a 300 mm lens a 16:1 magnification ratio is achieved). The use of automatic focus is not recommended due to the extra weight of the reverse-mounted lens. Attempted use of automatic focus with this technique could result in damage to the camera or lens. Working distance is significantly reduced as compared to the original lens.
  • The shallow depth of vision in macro photography requires narrow aperture.Flash or low shutter speed is required for filming with narrow apertures.The normal flash unit do not deliver adequate lighting.Ring flash or twin light horse shoe flashes solve this problem.They are mounted in front of the lens with special adapters.These units are quite expensive when compared with normal flash units.

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