f-Value
f-Number (f-Stop) ExposureThe ratio of focal length to aperture diameter.
The ratio of focal length to aperture diameter. f/2.8 on a 50mm lens means the aperture is 50/2.8 = 17.9mm wide. Each full stop (f/2.8→f/4) halves the light.
The ratio of focal length to aperture diameter.
The ratio of focal length to aperture diameter. f/2.8 on a 50mm lens means the aperture is 50/2.8 = 17.9mm wide. Each full stop (f/2.8→f/4) halves the light.