Generalities and specificities of macro photos
Macro photography consists of taking very close photographs of objects or animals (often insects or spiders), capturing a lot of detail. Strictly speaking, we speak of macro when we reach a reproduction ratio of 1:1 (the subject is as big on the film or sensor as in reality).
Macro is a very technical discipline, which requires a lot of material and knowledge in photography (exposure and sharpness can be particularly tricky to manage).
That said, the macro allows you to enter an exciting and magical world.
Settings and techniques for macro photography
Box: a compact box or bridge with a macro mode, or a reflex
Focal length: rather long (~50, 100, even 200mm.), offering a very short minimum focusing distance (20 or 30 cm.)
Accessories: close-up lenses to increase the magnification of the subject (but implies a loss of quality), extended rings to decrease the focusing distance (but means a loss of brightness), a flash can be useful because you often need a lot of light in macro
exposure and light measurement:
White balance: automatic outdoors or specific to artificial lighting (flash, tungsten bulb, etc.)
Metering mode for exposure: prefer spot metering to optimize exposure over one particular area, matrix/multizone metering or center-weighted metering to optimize exposure for a more significant portion of the image (a compromise between subject and background brightness)
Speed: use a reasonably fast speed (~1/100s. minimum), since you are very close to the subject the slightest movement on your part is “amplified.”
Aperture: in macro mode a small aperture (f/2.8 or f/4) results in an extremely small depth of field (barely a few millimeters), to obtain a larger PDC, close the diaphragm (f/11, f/16) openly, try not to exceed f/22 unless it is essential (because of the diffraction phenomenon which will reduce the image quality)
Sensitivity: preferably at least (~100-200 ISO), but the need for reasonably fast speed and a small aperture may require you to increase the sensitivity, try not to exceed ISO 400 or 800 depending on the performance of your body
natural light: avoid direct sunlight, which causes hard shadows; nevertheless, look for as much light as possible (outside in cloudy weather, close to a window inside)
artificial light: use a flash if necessary; ideally a flash that you can control remotely (from the camera) and place next to or behind the subject; set the flash as close as possible to the subject to obtain soft shadows, and move it slightly away to harden the shadows a little
composition: make a close-up shot of a part of the subject or show it in its entirety, frame wider to include the environment, etc.