© Jonathan Jamar 2011, EOS 50D
You see a similar result if you turn your camera up to photograph a tall building. The sides of the building appear to get close together, an effect called converging verticals. If you want to lessen this effect you need to stand well back and to keep the camera level with the ground.
Another powerful compositional aid is the S-line. Imagine a river starting in the foreground and curving away in an S-shape. Your eye will instinctively follow the line into the image. The S could be a road, a line of hills or a pattern in a close-up subject. Watch out for an S-line and use it in your compositions.
Imagine your picture divided into nine rectangles by two vertical lines and two horizontal lines, equally spaced. If you place your main subject on any one of the four intersections, the image will usually have a well-balanced appearance.
PowerShot and IXUS cameras offer the opportunity to display overlaid grid lines which can help to apply the rule-of-thirds on the LCD screen as you shoot.