Leaning Tower of Pisa is famous because of its tilt. Photographs show it as tilting bell-tower, getting ready to fall. Beautiful and interesting! However, if you are photographing anything else, tilted buildings look weird. We don’t see the buildings around us falling over so why should our cameras do so?
When we look at a building while standing on the ground floor, our mind automatically adapts to the change in the angle of view and the building looks normal. Our eyes are special when you consider the extensive processing that happens in our brains (Our Eyes vs Camera). When we tilt the camera up to photograph the building, the upper parts of the building are further away from the camera than the base and so the upper parts appear small on the photograph. So far so good. The trouble starts when we view this photograph. The various parts of the building on the print or the image on the computer are at the same distance from our eyes. The building then appears to be falling back. To some extent, our brains expect the distortion but when the buildings stand straight, they look better. More so when the camera is placed close to the building, as is the case with wide-angle lenses. The change in perspective by moving close exaggerates this falling-over tendency.
Prevent building from falling over-
Most architecture photographers use view-cameras with bellows that enable the lens to move upwards (as shown in the illustration below). The camera is not tilted. This ‘raising’ the lens results in a straight building on the final photograph. With DSLRs there are some tilt and shift lenses available but the freedom of lens movement is not the same as that in a view camera.
The easiest and most practical solution is to keep the camera parallel to the ground. If the camera is not tilted up, the building will not appear to fall back. A distant shot of the building without tilting the camera up can maintain the building straight. This limits the building to a part of the frame though. Either include a good foreground (maybe the courtyard, entrance or the driveway) or be ready to crop in post processing. See the image of the church in Religion and Photography article.
(An old church which appears to fall back. Photographed with a 25mm lens on a full-frame camera. The wideangle lens and close proximity of the building has further increased this distortion increasing the illusion of ‘falling back’.)
(The same church which appears to stand erect.Notice the bell tower on the left and the side of the building which is in shade.)
Some of the image editing programs provide the option to correct the falling buildings. Adobe includes this under lens correction. These programs achieve this by stretching the upper part of the image more than the lower parts. Gimp provides a very simple ‘Perspective Tool’. As you would have guessed, the stretching can sometimes look unnatural and it also results in data loss. Be careful when correcting this and make sure that the building looks natural to look at rather than being geometrically correct. Quite often this may involve stretching the image after correcting the perspective. As I mentioned before, the aim here is to make the structure straight while maintaining what looks natural.
(Screenshot of perspective tool from Gimp. Experiment with each option and learn to use this. Gimp is open source and free. For details of each option, refer to the Gimp’s manual.)
Falling effect can be interesting too
Sometimes the effect can be used intentionally to show the height of the building. Architects are famous for using this diminishing with distance effect to exaggerate the effect of their creations. Be it the Potemkin stairs in Odessa (Ukraine) or the Qutub Minar in Delhi (India), architects have made the upper parts smaller in size than the lower parts to use this effect. In photographs, a feeling of height can be provided by intentionally going close to the building and tilting the camera up. Very effective for conveying the heights of tall structures.
(Tall building which looks really high due to the falling back illusion or converging lines.. whatever you may wish to call it. Nikon D200 with Nikkor 18-55mm lens, f/8, 1/250 sec at ISO 100)