Find a scene that has depth. From a fixed position, take a sequence of five or six
shots at different focal lengths without changing your viewpoint. (You might like to
use the specific focal lengths indicated on the lens barrel.)
As you page through the shots on the preview screen it almost feels as though you’re
moving through the scene. So the ability to change focal lengths has an obvious use:
rather than physically moving towards or away from your subject, the lens can do
it for you. The other immediate difference between the shots is the ‘angle of view’,
which also depends on the sensor size of your camera. Use the sequence to try to
get a feeling for how the angle of view corresponds to the different focal lengths
for your particular camera and lens combination. Which shot in the sequence feels
closest to the angle of view of your normal vision?
Does zooming in from a fixed viewpoint change the appearance of things? If you enlarge and compare individual elements within the first and last shots, you can see that their ‘perspective geometry’ is exactly the same. To change the way things actually look, a change in focal length needs to be combined with a change in viewpoint.
Below is a sequence of 5 shots I took on the South Bank Friday lunchtime with my Fujifilm X30 compact camera. The sequence does give the appearance of travelling through the image. They were all taken with:
- Aperture priority
- ISO 100
- Fujifilm X30 equivalent 35mm focal lengths of:
Of all the images taken, the image taken at a focal length of 50mm appear to me the closest to normal vision.