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Genres in practice3 min read

LESSON 39

Macro

Small worlds at life size and beyond.

IN THIS LESSON

  1. What makes a picture macro
  2. Close-up versus true macro
  3. The depth-of-field problem
  4. In practice: light and steadiness

What makes a picture macro

Macro photography is extreme close-up work in which the subject appears larger than life. The key number is the reproduction ratio: the size of the subject on the sensor or film compared with its real size. At 1:10 the image on the sensor is a tenth of the real object; at 1:1 it is life size. In the strict definition, a macro picture is one made at 1:1 or larger, and a macro lens is one that can reach 1:1 or more, such as 2:1. Above about 10:1 the work becomes photomicrography, usually through a microscope. The term photo-macrograph was proposed by W. H. Walmsley in 1899.

Close-up versus true macro

Many lenses sold with the word macro on them only reach between 1:2 and 1:1, which is strictly the close-up range. That is still far closer than an ordinary lens, which usually stops at about 1:10 at its nearest focus. What the viewer sees is a separate matter. A small print or a phone screen enlarges the sensor image again. The source works an example: a 150 by 100 mm print from a 36 by 24 mm frame is enlarged about four times, so a lens set at 1:4 already gives a life-size result on that print.

The depth-of-field problem

The closer you focus, the thinner the zone of sharpness becomes, because depth of field shrinks with the square of the distance. At macro distances it can be a millimetre or less, so an insect's eye may be sharp while its legs are already soft. Stopping down helps, but past a certain point diffraction blurs the whole image and the light drops. Many macro photographers therefore take several frames at slightly different focus distances and merge them, which is focus stacking; lesson 56 explains the method. Lesson 53 explains depth of field itself.

In practice: light and steadiness

This section is working practice. At high magnification every tremor shows, so use a tripod or brace yourself, and a fast shutter or flash for living subjects. Move the whole camera back and forth to focus rather than turning the ring; it is easier to find the exact plane. A small diffused flash or a white card close to the subject fills the shadow your own lens throws. Early morning, when insects are cold and slow and the air is still, is a good time to try. Treat living subjects gently and put them back where you found them.

Try it today

  1. 01Find something small with texture: a leaf, a coin, a watch, a flower.
  2. 02Set your lens to its closest focus and see what ratio it reaches.
  3. 03Lock focus, then rock the camera slowly forward until the detail you want is sharp.
  4. 04Shoot the same subject at f/4, f/8 and f/16 and compare depth and softness.
  5. 05Add a white card opposite the light and see the shadows open.