Correcting Converging Verticals
Professional photographers who take pictures of architecture and interiors use specialist equipment such as shift lenses or medium and large format cameras where lenses can be tilted and shifted in all directions as they use a flexible bellows system. Shift lenses are very expensive but in the past, they were the main option for correcting converging verticals when photographing large buildings. Wide angle shift lenses made for 35mm cameras by Nikon, Canon, and Olympus are only of use on digital SLR cameras which use a full frame sensor.
Most digital SLR sensors are much smaller than standard 35mm film and therefore a 28mm shift lens will become the equivalent of a standard view 42mm lens. To overcome these limitations, other alternative methods must be used for correcting converging verticals. Fortunately there are a few other options which involve significantly lower costs than purchasing a shift lens and a full frame digital SLR.
With digital photography, it is possible to take photographs of architecture on a standard digital camera and then correct the converging verticals by using the lens correction option in recent versions of Adobe Photoshop. This option can be found under the Filter - Distort menu. The lens correction option offers precise controls over transforming horizontal and vertical perspective as well as vignetting. Also, it offers options for minimizing other lens problems such as chromatic aberration. An example of converging verticals can be seen in the image below on the left. The corrected image, after processing in Adobe Photoshop, can be seen below on the right.