Depth of Field: f-stop Exercise
To learn the effect of aperture (f-stops) on depth of field, take a series of photos of the exact same shot. Start at the smallest aperture (largest f-stop number) and with each shot open the aperture by 1 f-stop. You will have to re-expose each shot by decreasing the shutter speed, or to simplify, put your camera in aperture priority mode. With each shot you will notice a decrease in the depth of field, look at the metadata from each shot to get a better feel for the effect.