Focal Length and Perspective
Technique - Technique


There's a bit more about the focal length than just the coverage of a certain angle of view - there's always distinct effect on the relationship between the objects within a scene.

All picture by Michael Wagner.

Let's have a look at a relatively wide focal length first: 28mm. The following image samples show 4 trees with an equal distance between neighbor trees. At the wide setting it seems that this distance actually increases dramatically towards the foreground (exponential behavior of the distance). It other words: the tree to the left seems to be totally separated from the rest of the gang. The background seems to be far in the distance.

The next picture has a more natural view at about 50mm. The perspective is obviously much less extreme. Due to our real life experience we can guess that the distance between the trees is roughly the same though the separation is still visible (d^2 behavior).

Now we have a 100mm lens. The trees seem to group here with a seemingly small distance between the trees. Compared to the previous sample the now enlarged background suddenly moved towards the main object. The scene is compressed now.

At 200mm the effect increases even more. The group of trees seems to be virtually on the same distance plane. The background may be blurry (due to the small depth-of-field) but it seems to be just a few meters away. We speak of a "flat" perspective is this case.