Choosing a lens for macro

Macro is the one category defined by a single number: maximum magnification, or how large a subject is reproduced on the sensor. At 1× (life size) a 10mm insect is projected 10mm across. At 0.5× it is 5mm.

Why 0.4× and up

Manufacturers put “macro” on lenses that reach 0.25×, which is really just close focusing. From about 0.4× you can genuinely fill a frame with a flower or a watch face; 0.5× is called half macro; 1× is what most people mean by the word.

This list filters on magnification rather than on the word “macro” in the name, which is why some lenses badged macro do not appear.

Focal length changes working distance, not magnification

A 50mm and a 100mm macro both reach 1× — the difference is how far away you stand. The 50mm has you almost touching the subject, which blocks your own light and frightens anything alive. 90–105mm is the usual compromise, and 150–200mm is what people photographing insects choose.

Depth of field is measured in millimetres

At 1× and f/2.8, the plane of focus is under a millimetre deep. Macro work happens at f/8 to f/16, which means you need light — and it means a fast maximum aperture is close to irrelevant for this use. Do not pay for f/2.8 if macro is the only reason.