Vertical images are best used:
- When the subject is vertical
When your subject is taller than it is wide, a vertical image compliments the subject. - To allow the subject to move vertically
When your subject is moving up or down, using a vertical format in conjunction with the rule of thirds visually allows the subject room to continue moving. This will amplify the sense of motion in the image. This is also true of subjects looking to up or down. Having open space to the top of bottom allows the subject's gaze to continue farther than is possible in a horizontal image. Remember also that when a subject is moving deeper into an image or moving towards the camera that this appears as "up or down" movement when converted into a 2D image. This is why many leading lines images work very well as vertical images. - To focus attention
Vertical images can be used to focus a viewer's attention on a single subject by removing almost all sense of peripheral vision. This is the theory behind portraits and other single-object compositions and can be combined with either the rule of thirds or centering to intensify impact.
