Olympus E-PM1 with Olympus 14-42mm lens
1/400 second at f5.6 and ISO 200 and +1.3 exposure compensation
In the photo straight out of the camera, the verticals converge towards the top of the image. This is because of the simple fact of pointing the camera upwards in order to get the whole of the building in the frame.
Some subjects suit converging verticals. But if you don’t want them, there are three ways to deal with the ‘problem’.
One way is to use a rising front – which is a lens that splits so that the front half of the lens can be moved up or down relative to the rear. It’s an expensive option and most often used by professional photographers specialising in architectural photography.
Another way is to climb up high into a building opposite the one you want to photograph. That may seem funny, but Ansel Adams had a ladder fitted to the top of his van which he propped up vertically when he found a suitable subject, so that he could gain height from which to photograph.
And the third way is to correct the verticals in post processing. There are a number of tools in photoshop for carefully correcting distortion in a photograph.
The problem with converging verticals is that as you drag the verticals into line, the height of the building is reduced and becomes too squat. So then you need to stretch it vertically to its correct proportions. The problem then is that you will tend to run out of vertical space within the frame.
To deal with this, I increase the canvas size at the top of the image and then stretch the building back into shape. It avoids the problem of not having anywhere for the building to be stretched into.
It’s easier to show than to explain, so I’ve made a short video to show the process from beginning to end: