Some cameras do this automatically, and will adjust the focusing distance in steps in order to obtain a larger depth of field. It's mostly used in macro photog

Some cameras do this automatically, and will adjust the focusing distance in steps in order to obtain a larger depth of field. It's mostly used in macro photography, where the depth of field is less than a millimeter thin, although it's sometimes used for landscapes too if there are elements in the composition that are very close. As for lenses that have more depth of field, having more depth of field requires a smaller shutter, which means that less light enters to hit the sensor. A shutter that's too small will also be less sharp due to diffraction. So in practice, it's necessary to do focus stacking in certain scenarios.