How many photos from your last trip were shot in landscape format? Maybe 95 percent, or 98? Holding the camera in landscape format is much more logical and comfortable, and it corresponds to our natural perception (our eyes are next to each other, not on top of one another). In many cases the landscape format seems like the best option, and in many cases it is. But some subjects and pictures would greatly benefit from a change of format. It may seem like it’s more trouble and less comfortable to hold the camera in the portrait format, but the advantages outweigh the risks, not just with portraits.
All it takes is the courage to turn your camera 90 degrees. The first encounter with portrait format is often one of necessity: the subject simply won’t fit into a landscape-format image because the focal length is too long or because it’s impossible to increase the subject-to-camera distance. In many cases, however, a serious problem comes along with this use of the portrait format, first and foremost with urban photography – namely, converging verticals resulting from perspective distortions. Apart from that, the portrait format is much too valuable to serve only as a stopgap measure for these circumstances
Despite all the encouragement for making use of the portrait format, however, there are some potentially undesirable consequences to keep in mind. Photographers who show their images in slide shows may want to stick with the landscape format, as portrait-format photos are often difficult to integrate.
You also need to take caution when using the built-in flash for a portrait-format shot because the light will not be emitted from a point above the optical axis; instead, it will come from one side of the lens. Under certain circumstances this can result in an uneven distribution of light in your photo. External flash units, preferably with adjustable swivel heads, can prevent this problem, as they can be positioned away from the camera’s flash mount