Understanding F-Stops: f/1.8 vs f/22
DefinitionThe size of the hole in your lens that lets light in.
1The Simple Explanation
Think of the pupil in your eye. f/1.8 is a wide open pupil (lets in lots of light, blurry background). f/16 is a squinting pupil (darker, but everything is in focus).
2Technical Deep Dive
The f-number is the ratio of focal length to pupil diameter. f/1.8 has very shallow Depth of Field (Bokeh). f/22 has deep Depth of Field but suffers from diffraction.
Common Misconceptions
Myth: Bigger number = More light. Fact: Opposite. Lower number = Wider hole = More light.