How to eliminate the need for perspective correction.

Perspective correction is often a challenge.  We all faced this challenge when photographing a building.  The building appears to falling backward due to converging lines. This problem is common and when I headed to take a photo of the Basilica “Notre-Dame de Montréal”, I knew that this was a challenge.

This problem occurs when you tilt the camera upwards to keep the entire building in the viewfinder.  When you keep your camera leveled, the picture do not show these converging lines.

How to solve this?

Using a Tilt and Shift lens:

Tilt and Shift lenses help solve perspective correction problem. They help keep the camera leveled by allowing the lens to shift up.  When shifting the lens up, the image circle projected on the sensor is also higher in the scene.  Because of this property of these lenses, it is easier to keep the camera leveled and the subject in the viewfinder, depending on the focal length, the distance between the camera and the building and its height.

These lenses are expensive and need manual focusing.  They are usually found in the hands of photographers specializing in architecture.  Another use is in landscape photography to get everything in focus.

The great advantage of these is to maximize the effective use of the sensor and to avoid software transformations that are source of artifacts.

Correction in software such as Lightroom:

You can also use software to correct perspectives after the fact.  Lightroom does a very good job at perspective correction. Through mathematical algorithms, Lightroom will insert new pixels in the picture to allow these structures to take volume.  The upper part of the picture will expand while the bottom part cropped.  It is important to frame wider than the subject to account for cropping.

Another drawback, those added pixels will never be as good as the reality. To display on the web, that’s usually good enough.  A large-format print might show imperfections.

These two scenarios also allows the photographer to shoot while at a reduced distance.

Keeping the camera leveled:

Keeping the camera leveled is the easiest way to make such a picture. This means however that you are able to move away from the building and use a wide-angle lens. Most of the time it is very difficult to move away enough to keep the building in the viewfinder. You either don’t have enough space to do so or there are so many distractions in the scene that the picture would not work.  Another impact is that you lose almost 50% of the image to cropping.  Your great 20 mpix sensor will produce only 10 mpix in that scenario.

Another impact is compression of the distance between the distant subject and objects at mid distance.  As if taken with a telephoto.  By moving farther away and eliminating almost 50% of the picture to cropping, your wide-angle lenses will compress the perspective instead of exaggerating the distances between objects.

About this photo:

I took this photo while keeping camera leveled and moving farther away from the Basilica.  This was a luxury I could afford.  The “Place d’Armes” in front of the building was empty at 6:05 in the morning. I then removed the bottom part of the picture by cropping in Lightroom.

I must confess that I played a trick to my colleagues in the Photo Club. Showing them the picture I asked them if it was a tilt and shift lens or a software correction that led to such a nice perspective.  Now I need to apologize… It is rather difficult to spot what I did in this case. The only clue could be the Maisonneuve monument, in the middle of the Place d’Armes, which is clearly visible to the right of the Basilica.  The monument was in that place because I was very far away from the Basilica when I took the picture.

In conclusion, when possible, stay away and keep your camera leveled when taking pictures of buildings. This will give you a different perspective. Unless of course you have a tilt and shift lens in your bag…