Keystoning

Usually found in Architecture_Photography, keystoning is the converging of lines that, logically, should be straight, usually toward the top of a tall building.

The effect is caused anytime your camera is not pointing horizontally away from you; when you point it up or down from right in front of you.

• Keystoning can be solved (assuming you are not going for the effect on purpose) by backing up and using a longer lens to get your subject, the use of a very expensive tilt-shift lens, or the use of the Free Transform tool in Photoshop or other post-processing software.

None at this time.