Since a picture is two dimensional (2-D) and your foot is a three dimensional (3-D) object, we prefer to take a least 3 views of the foot.  Typically, it is one straight up and down, one side view, and one diagonal view. This way, we can "look" at the bones in the foot from different perspectives to make an accurate diagnosis.  In addition, there are certain views that are standard across the board in radiology, so anyone taking weight bearing views of your foot will have certain settings that allow the doctor to compare apples to apples in a sense.  Sometimes we will take a contralateral view, which is a view of the other foot, to see differences between the feet or if we detect an anomaly.