Macro Photography Quiz

Magnification of 1:1, or life size, means the subject is projected onto the sensor at its real size, so a 10 mm insect covers 10 mm of the sensor. That is the standard definition of a true macro lens. A ratio of 1:2 is half life size, often sold as close-up.

At macro distances, depth of field shrinks to millimeters or less, even at small apertures, because it decreases sharply as magnification rises. That is why focus stacking is common in macro work. ISO has no effect on depth of field.

Working distance is measured from the front element of the lens to the subject. It determines how close the photographer must physically be to fill the frame at a given magnification, and affects whether a subject is disturbed by the presence of the lens.

Extension tubes are hollow spacers with no glass that move the lens farther from the sensor. That lets the lens focus much closer than normal, which increases magnification. The focal length itself stays the same, and the extra distance costs some light.

A ring flash wraps around the front of the lens, so its light comes from the camera axis and from all sides at once. At macro distances that gives even, nearly shadowless light on small subjects that the lens itself would otherwise shade. It is not especially powerful.

Diffraction softens detail as the aperture gets smaller. In macro the effective aperture is already smaller than the marked one because of magnification, so f/22 at life size acts like about f/44 and visibly blurs fine detail. At f/2.8 diffraction softness is negligible.

A reversing ring screws onto the filter thread so the lens can be mounted backward on the camera. Reversed, a normal or wide lens focuses only very close and gives magnification around life size or more, a low cost route into macro. It cannot focus to infinity in that position.

In macro and product work, a single frame often cannot hold the whole subject in focus because depth of field is so thin. Focus stacking shoots several frames focused at different distances and blends the sharpest parts, giving a final image that is sharp from front to back.

Extension tubes move the lens farther from the sensor, so the light spreads over a larger area and less reaches each part of the sensor. The effective aperture becomes smaller than the marked f-stop, often costing about two stops at life size. They contain no glass, so they do not reduce sharpness or add color shifts.

At high magnification, the smallest movement shifts the frame and the thin plane of focus. A tripod holds the camera still, and a cable release or self-timer fires it without touching the camera. A monopod still allows sway, and high ISO only shortens the exposure.