What Can Make a Line?Almost anything can create a line within a photograph. There are three main categories of lines that can be used in leading lines. These are: natural, man-made, and suggested.
Natural leading lines are things such as rivers, tree tops, edges of flower patches, geese flying in formation, or even an alligator’s tail. Anything that creates a continuing line within your frame can be used as a leading line.
Manmade leading lines are lines that do not naturally occur in nature. Manmade lines can be things such as roads, power lines, rooftops, fences, rows of windows or doors, support structures for bridges, or the bridges themselves. As with natural lines, the composition of the line isn’t important as long as it creates a solid pathway for the eye to follow.
This is where leading lines gets a touch tricky, and perhaps a little controversial. Not everyone calls a suggested leading line part of the leading line composition rule. Because it falls into lines, I prefer to consider it part of leading lines rather than a wholly separate tool. A suggested leading line is a broken line or an absent line that is strongly suggested by the positioning of items within the frame. These suggested leading lines are most frequently due to line of vision. This is when a subject in the frame is looking directly at a specific point with nothing between the two to visually separate them. For example, a person holding an apple and looking at the worm crawling out of the apple with the background strongly blurred between the face and the apple/worm. In addition to the lack of separating objects between two points in a suggested leading line, it works best when the distance between the points is the shortest comfortable route for the eye to take. This means that while the distance might be longer for the eye to wander around the frame a bit, if another composition tool is present that suggests a different visual path (say the rule of thirds), the eye will follow the other progression of sight instead of the suggested leading line. In other words, if in our hypothetical subject looking at the apple/worm photo there was a large bee on a rule of thirds intersection point above the main subject’s head, the eye of your viewer would be drawn away from the suggested leading line to that blasted bee so that the visual path might be subject-bee-apple/worm instead of subject-apple/worm. Use caution when attempting a suggested leading line as the composition has to be just right for it to work strongly. However, if everything comes together properly it is a powerful option for a leading line.
Do the Lines Have to be Straight?No, lines do not have to be straight. In fact, some of the most interesting lines are curved or even looped. As long as there is a definite path for the viewer’s eyes to follow, the line can take any path you wish. For example, a twisted road leading up a mountain still works as a leading line although it takes the eye through a twisted path within the photo.
Using Sets of Lines TogetherOne of the most obvious and often used lines is a railroad. The rails themselves are strong lines that are usually in strong contrast with the surroundings. However, the gravel beside the tracks creates lines and the tree tops (or power poles) following the tracks create even more lines. Because these lines all work together and run in the same direction, the strength of the railroad line is greatly increased by the support of the secondary lines around it.
You can also use converging lines together. A flock of geese in a V formation is actually two lines coming together at the point of the V. In this case you have two lines joining and the eye follows those two lines like an arrow pointing to the intersection of the line.