This was shot at f/10 and focused on the girl who was pushing the cart.
Both was not focused correctly that resulting the background slightly out focus. It is all right for the overall effect. But how do I get everything in focus, in this case the children playing in the background.
For 35mm lens on a full frame camera, at f/8, the focusing point should be at 18 feet then everything from 9 feet to infinity will be in focus.
For 35 mm lens on a full frame camera, at f/11, the focusing point should be at 12 feet then everything from 6 feet to infinity will be in focus.
1 meter is about 3.3 feet or 10 feet is 3 meter. I am 172 cm or 5.64 feet in height. When spreading my arm, the distance from the tip of my middle finger of right hand to that of my left hand is the same as my height. A good yard-stick in field to estimate the distance.
Thus the way to focus is use single point and AF-S, pointing the focusing point on a subject at the desired distance, focus then recompose and shoot.
If the main subject is too close (closer than 6 - 9 feet, closer than 1x to 1.5x of my height) to be in focus with the background, back out to the desired distance and crop the picture later on.