Focal Length and Angle of View
Using my back garden as the scene for this first exercise, I took three images at different focal lengths: 18mm, 55mm (my angle of view) and 200mm.
I measured my angle of view by looking through the viewfinder at the scene with one eye and at the scene (unaided) with the other eye and changing the focal length until the two scenes matched. I then recorded the focal length.
The following are the settings I used for each image to achieve the correct exposure:
18mm – 180mm distance
55mm – 555mm distance
200mm – 2000mm distance