There is a very popular rule in photography, known as the rule of thirds. While we all love that rule, it is often difficult to put all images in the same rule. The rule states that if the picture frame can be divided by four imaginary lines, two vertically and two across, the points where they would intersect would be the main focus points of the human eye. This is why it would be justifiable to put the main subject of the picture on one of those intersecting points. The principle is to keep your main subject a bit off center. You can ply the rule in three ways
The Horizon – you can simply put your horizon on or close to any one of the horizontal line. Putting your horizon on upper horizontal line will emphasize the foreground subjects & placing it on lower horizontal line will emphasize the background ( for example “the sky”.
The Vertical lines – placing your main subject on any of the vertical lines, will make your subject off-center and help you to balance the negative space.Good for Vertical object.
The four intersecting points – they work as same as vertical lines. Works well for portraits, flower, Still life etc. Sinply place your subject of interest on any of the power points.
But the rule of thirds is not applicable in all situations. At times, it is necessary to put the subject at the center of the frame. It is all a matter of logic and what looks best on the frame. Photography is a form of art that is still evolving and provides photographers with ample chance to experiment.