Macro photography

Macro photography is a kind of photography. Macro photography is about photographing objects that are very close to the lens, the film or the sensor. Using the classic definition, in macro photography the image shown on the film plane (or sensor) is nearly as big as the object photographed. There are different ways to achieve this. The most common one is to use a specialised macro lens. Such lenses are good at focussing sharply on a small area approaching the size of the film frame. Most 35mm format macro lenses achieve at least 1:2, that is to say, the image on the film is half the size of the object being photographed. Many 35mm macro lenses are 1:1, meaning the image on the 135 film is the same size as the object being photographed. Another important difference 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 6x4 inch (15x10 cm) print is made, the image is life-size or larger. With 35mm film this requires a magnification ratio of only approximately 1:4, which demands less of lens quality than 1:1. With digital cameras the actual image size is rarely stated, so that the magnification ratio is largely irrelevant; cameras instead advertise their closest focusing distance.
Typical subjects are still life, such as fruit, flowers, jewelry and small household objects. Macro photography often reveals details of the subject not visible with the naked eye.
Different ways to do macro photography
Using a specialised macro lens. These exist in different focal length, from what should be a normal lens (40-60mm for 35mm flim), to medium to long telephotos (around 100mm, and 180-200mm). Very often they offer reproduction ratios of 1:2, or 1:1.
Sometimes ordinary lenses have a macro position. They usually offer reproduction ratios around 1:4.
Using what are called extension tubes. These are small inserts between the lens and the camera. They move the lens farther away from the camera, increasing reproduction ratio, decreasing depth of field. The main problem with that is that they cost light, usually cutting brightness by a factor between two and four. It may also be impossible to get a sharp view of the object photographed, if it is farther away. An extension tube where the distance can be changed continuously is called bellows.
Using a close-up lens, in front of the lens. This will act like a magnifying glass
Using a telephoto extender. This will change the focal length of the lens, and give a bigger image.
Problems with macro photography
There are two main problems with macro photography:
The Depth of field can be extremely shallow. This means that objects that are even a millimetre closer of farther away can be out of focus - blurry.
Getting enough light: The more magnified an image is, the more difficult it is to get enough light. There are also special flashes, called ring flashes. These are mounted on the lens. Another option is to use a telephoto macro lens (which is more expensive). This means working distance is increased.