How to shoot with a small depth of field, such as how much to adjust the aperture?

Generally speaking, it is difficult to capture a small depth of field with a small DC, but it is much easier with a SLR.

The depth of field depends on four factors: the distance from the subject to the lens, the effective pupil diameter, the focal length of the lens and the maximum allowable fuzzy circle.

Among them, the influence of lens focal length on depth of field is relatively more obvious. The maximum allowable fuzzy circle is basically 1/20mm.

For small depth of field, please try: use a large aperture (small F value), bring out the telephoto with the telephoto, and get as close as possible to the subject.

Try to practice more, and you will have more experience. I believe that the landlord can learn more and better things through continuous practice!