The depth of sharpness can depend on the three most basic parameters:
Diaphragm
The main parameter with which we can regulate the depth of sharpness is of course a diaphragm. To reduce the flu, we need to open the diaphragm as wider as possible, that is, reduce the number of diaphragm. To increase the flu, we need to close the aperture more, that is, increase the number of diaphragm. On different lenses, the minimum and maximum numbers may vary slightly, for example, values can begin with 1.4 or 2.8, and end 16 or 22. It is extremely not recommended to close the diaphragm completely to a value of 22, because there can be diffraction and too soft image.
