Infinity focus

[1] In practice, not all photographic lenses are capable of achieving infinity focus by design.

Failure of the human eye to achieve infinity focus is diagnosed as myopia.

Focus mechanisms must accommodate part variations; even custom-built systems may have some means of adjustment.

For example, telescopes such as the Mars Orbiter Camera, which are nominally set to infinity, have thermal controls.

Deviations from its operating temperature are actively compensated to prevent shifts of focus.