Select your longest focal length and compose a portrait shot fairly tightly within the
frame in front of a background with depth. Take one photograph. Then walk towards
your subject while zooming out to your shortest focal length. Take care to frame the
subject in precisely the same way in the viewfinder and take a second shot. Compare
the two images and make notes in your learning log.
As you page between the two shots it can be shocking to see completely new
elements crash into the background of the second shot while the subject appears
to remain the same. This exercise clearly shows how focal length combined with
viewpoint affects perspective distortion. Perspective distortion is actually a normal
effect of viewing an object, for example where parallel train tracks appear to meet
at the horizon. A ‘standard lens’ – traditionally a 50mm fixed focal length lens for
a full-frame camera (about 33mm in a cropped-frame camera) – approximates the
perspective distortion of human vision (not the angle of view, which is much wider).
A standard lens is therefore the lens of choice for ‘straight’ photography, which aims
to make an accurate record of the visual world.
Below are 2 shots I took near the South Bank Friday lunchtime with my Fujifilm X30 compact camera. The pair of images are framed on the sign. They were all taken with:
- Aperture priority
- ISO 100
- Fujifilm X30 equivalent 35mm focal lengths of:
The difference in the view between these two images is striking considering the fact that the subject occupies the same space in the frame.