A. The closer you are to a subject the less depth of field you will have.
B. The wider your aperture the less depth of field you will have.
DOF MORE LESS
Aperture Setting F22 F1.4
Focal Length Wide Angle Telephoto
Shooting Distance Far away Close-up
The point at which you should focus to get the maximum depth of field in your photograph.
Depth of field extends 1/3 in front and 2/3 behind where your focal point is.