Lenses
Macro Magnification
The ratio between the size of a subject as projected onto the sensor and its actual real-world size. A 1:1 magnification means the subject is projected life-size onto the sensor. Higher magnification ratios allow smaller subjects to fill the frame.
Macro magnification is expressed as a ratio: the size of the subject's image on the sensor divided by the actual size of the subject. A 1:1 ratio, often written as 1x, means a subject 17.3mm wide exactly fills the width of a Micro Four Thirds sensor. A 2:1 ratio means a subject 8.65mm wide fills the same sensor width — the subject is magnified to twice its real size on the sensor. Higher magnification ratios allow the photographer to fill the frame with progressively smaller subjects.
True macro photography is conventionally defined as shooting at 1:1 magnification or greater. Lenses marketed as macro but offering only 1:2 (0.5x) maximum magnification are not true macro lenses by this definition, though they can still focus closer than standard lenses. In the Micro Four Thirds system, dedicated macro lenses that achieve 1:1 include the Olympus 60mm f/2.8 Macro, the OM System 90mm f/3.5 Macro IS Pro (which reaches 2:1), the Panasonic Leica Macro-Elmarit 45mm f/2.8, the Olympus 30mm f/3.5 Macro, and the Panasonic 30mm f/2.8 Macro.
The effective field of view at 1:1 on M43 is a 17.3 x 13mm area — the size of the sensor. At 2:1 on the OM System 90mm f/3.5 Macro IS Pro, the field of view shrinks to approximately 8.65 x 6.5mm, making it possible to fill the frame with a small insect's eye or the surface texture of a coin. Depth of field at high magnification ratios is extremely thin — often less than a millimetre at typical apertures — making focus stacking a common technique in macro photography to achieve adequate sharpness across the subject.