In advance of taking a picture, set focus by using rangefinder around where the object will be or estimate the distance to the will-be-object and set that distance with the distance ring on the lens.
And then, see the depth of field scale on the lens if its range is satisfactory for the object.
If not, decrease the aperture so as to deepen depth of field and re-select the shutter speed matching to the aperture.
As the object is nearer to the camera, depth of feild is shallower, and the farther, the deeper.