Macro Photography

What is Macro Photography?
Macro photography means to record a subject at life size on the negative or sensor. That means that the image on the negative is the same size as the subject in real life. In common usage, however, macro photography simply means an extreme close up image.

Methods for Achieving Macro Photography
There are two main tools used to achieve macro photography images. These are macro lenses and extension tubes. Macro lenses are marked with a ratio such as 1:1 or 1:2. Some high end lenses can even provide larger than life magnifications such as 5:1. Extension tubes are hollow tubes of varying lengths that increase the focal distance of the lens by moving the lens elements further from the film or sensor. Extension tubes on current cameras generally disables the autofocus feature.

Depth of Field in Macro Photography
When working with macro images depth of field is greatly compressed. A small aperture (large F-stop) such as F22 might give a depth of field of nearly a mile in normal photography, with macro photography it might only give an inch or less of clearly focused area. This compression comes from the extremely small distance required between the lens and subject as well has the high magnifications often used in macro photography. Because of this depth of field compression, precision focus and stable equipment is essential.

Focus in Macro Photography
Because subjects of macro photography are often very small and the compression factor of the depth of field focus must be very precise. Due to this, a tripod or other stable support is greatly recommended even if using a high shutter speed. If you hand-hold the camera any forward/backward motion of your body will affect the focal point of the image. If a tripod or other stable support is not an option due to location or subject speed, use the fastest shutter speed possible to reduce the chance of body motion changing focal points. Also recommended is the use of manual focus. The depth of field in macro photography is often so small that only a piece of an insect or other subject will be in focus. It is essential in these cases that the “right” part of the subject is in focus. For example, a portrait of a dragonfly where the back of the insect is in focus but the face out of focus is not a good image. The face of the subject should be the focal point.

Subject Selection in Macro Photography
While macro photography focuses on smaller things, your subject does not necessarily have to be small. With subjects that are larger you simply focus on a piece of the subject. For example, part of the interior workings of a pocket watch or your pet’s paw could be a good macro photography subject.

Lighting in Macro Photography
Macro photography requires much more light than “standard” photography. This is because high magnification lenses and extension tubes lead to less light reaching the film/sensor. Also, the small apertures used to get as much depth of field as possible require much more light for an adequate exposure. If enough natural light is not available, fill flash and reflectors are good options.

Source : http://photography.about.com