Infinity Focus
The lens setting at which parallel rays from very distant objects converge on the sensor.
Measured in
m
In depth
For photographic purposes, infinity begins wherever further distance no longer changes the focus setting — around 100 times the focal length. Many autofocus lenses focus past infinity to allow for thermal expansion, so racking the ring to its stop does not guarantee sharp stars. Live-view magnification is the only reliable way to confirm it.
Examples in practice
A lens turned hard against its infinity stop renders stars as small discs; backing off very slightly brings them to points.