Whilst it is true that it can cost a small fortune to become involved in the world of close-up, macro, and micro photography, we have some basic items of equipment (mainly for film and digital SLR cameras) which enable a variety of techniques to be used at reasonable cost. Some basic definitions and simple mathematics help to put the various techniques into perspective:
CLOSE UP PHOTOGRAPHY is in the range 1:10and 1:1(1/10 to life size)
1:1 means that an image is recorded onto the film or sensor the same size as the subject. In other words, the diameter of a coin on the film or the sensor will measure as exactly the same diameter as the actual coin, not reduced or magnified in any way. Traditionally, lens designers have set the closest focus distance of any lens to give a ratio of 1:10 which means that the image of the coin would only be 1/10th life size. In order to focus closer the optical characteristics of the lens must be altered by fitting a special close up lens attachment to the front of the lens OR the position of the lens, relative to the film/sensor, must be altered. In normal use, the film/sensor in the camera is exactly coincident with the infinity image produced by the lens. Move the lens away, even slightly, and you can no longer focus to infinity, and the distance to which you can focus comes closer. The greater the displacement of the lens, the closer you can focus.
MACRO PHOTOGRAPHY is defined as between 1:1and 20:1(life size to 20x larger)
Any lens can be made to produce 1:1 by adding an extension between the lens and the camera which is exactly the same length as the focal length of the lens. i.e. 28mm for a 28mm lens, 50mm for a 50mm lens, and so on. Another fact is that the distance between the film and the subject when the lens is set to 1:1 is exactly 4x focal length, and the optical centre of the lens is exactly in the middle, i.e. 2x the lens focal length from both the film and the subject. Therefore, you can see that 1:1 is easier to achieve with a shorter focal length lens, but you will have less working distance. To calculate magnification, divide the added extension by the focal length of the lens. 200mm extension with a 50mm lens will give 4:1. However, another factor to consider is that by increasing extension, you decrease the light transmission to the square of the distance. In other words, if you double the extension, you quarter the light.
MICRO PHOTOGRAPHY is defined as magnification of 20:1 upwards.
This can be achieved by using very long extensions on standard lenses (1000mm for a 50mm lens!!) or by using short focal length lenses such as microscope objectives or lenses designed for 8mm or 16mm movie cameras. Extreme magnification photography is usually performed using a microscope.
