Focal Length Explained - The Focal Length Rule

You can tell how focal length dictates the pictures you can take by memorising the following rule. As the focal length of a lens increases, its angle of view decreases because the magnification increases, which results in the object becoming larger in size.

Focal length affects perceptual perspective too. As the focal length and magnification of a lens increases, the image appears more compressed, resulting in less visual distinction and separation between the foreground, middle ground, and background.

Wideangle - Standard - Telephoto

Focal Length Explained   - Focal length example image