Enrico Marega Interactive photography course
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Macro and focus stacking

In macro the depth of field becomes razor-thin, even less than a millimetre. Stopping down helps little, because diffraction sets in. The solution is focus stacking: lots of photos focused on different planes, merged into one.

1Simulator

Focus on a ruler or a flower

The classic macro test is a tilted ruler; then try the flower. Move the focus and watch the focus peaking, then choose the step and shoot the series to merge. The blur is exaggerated, as in a large print, so you can see it even on the screen of an iPhone or an Android smartphone.

Why stopping down isn’t enough

1Simulator At 1:1 magnification, when a real millimetre covers a millimetre on the sensor, the sharp zone at f/8 is about one millimetre. At f/22 it would be almost three, but diffraction softens the whole image: in macro the effective aperture is about double the one you read.

1Simulator Focus peaking colours the in-focus edges and it’s the best aid for manual focusing: almost all mirrorless cameras have it, sometimes called peaking or MF peaking. For stacking, many cameras shift the focus by themselves in regular steps: on Nikon it’s called focus shift shooting, on Canon, Sony and Fujifilm focus bracketing (not on every model). Then a program such as Photoshop, Helicon Focus or Zerene Stacker merges the shots.

Key points

  • In macro the depth of field is fractions of a millimetre: at 1:1 and f/8, about 1 mm.
  • Beyond f/11–f/16 diffraction makes the whole photo softer: stopping down isn’t the answer.
  • Focus stacking: lots of shots, moving the focus a little at a time, then merged. You need a still subject and a tripod.

Try it yourself

Lay a ruler at an angle on the table, or choose a flower, and photograph it as close as you can with the aperture wide open. Count how many millimetres are sharp. Then stop down to f/8 and f/22 and compare sharpness and depth.

Post the result and tag me @enrico.marega, or send it to me by DM: I’d love to see how you tackled it.

Quick check

Why don’t you always stop down to f/22 in macro?
You need 6 mm of depth and each shot covers 1. How many shots do you need, with a little overlap?