How the Rule of Thirds is Applied:

Consider the Rule of Thirds as a Guidline only. If you use it all of the time, it is hard to keep your images creative.



The rule of thirds is applied by aligning a subject with the guide lines and their intersection points, placing the horizon on the top or bottom line, or allowing linear features in the image to flow from section to section.

To Get the Perfect Grid: Divide the length of the image or picture frame into eight parts, and at the fifth mark from the left, draw a line from top to bottom. Count five parts, starting from the opposite side, and do the same thing. Draw two lines in the same manner from the width of the frame, and the end result is figure 1 as shown.

It's difficult to visually divide the viewfinder into eight equal parts. Therefore, it's easier to use the Rule of Thirds, which divides the viewfinder into three sections, both horizontally and vertically. As you can see from Figure 2 (at right), the Golden Mean is a tighter grouping than the Rule of Thirds. Both methods use the power point concept for placing the main subject(s).

Note that when photographing people, it is common to line the body up with a vertical line, and have the person's eyes in line with a horizontal one, therefore use the Rule of Thirds to help you get a better placed picture.

http://en.wikipedia.org/wiki/Rule_of_thirds#History
http://photoinf.com/Golden_Mean/Jim_Altengarten/Creativity_and_the_Rule_of_Thirds.htm