The 3:2 frame has stronger 'orientationality', with most photographs being taken in the horizontal orientation for three reasons: device ergonomics; human field of vision; and the portrait position is perceived as being too elongated.
The 4:3 frame being shorter and fatter, has less orientation bias and exerts less pressure on composition. It is hence less insistent.
The 1:1 frame, like the Polaroid or instagram images, is uncommon for good reason. Few subjects lend themselves to the "tyranny of its perfect equilibrium" (Michael Freeman 2007).
Switching orientations between landscape and portrait, arises out of necessity; although a composition works well in landscape, it may be necessary to re-orientate and re-compose in portrait due to full-page print requirements.
Vertical subjects in horizontal frames can be a challenge. One strategy is to offset the vertical subject to draw the eye horizontally across the photo.
Shooting vertically, there are two important factors to take into account:
- the human eye is more reluctant to move up and down than it is from side to side; and that
- the bottom of the frame is assumed to be the base, therefore the focus of attention tends to below the frame's centre.
Non-bias patterns are most immune to the impact of frame shape on their successful portrayal.