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Glite Dictionary
parfocal

parfocal

1 9.3
A lens that stays in focus when you change the zoom or magnification
  • adjective
  • /ˈpɑrˌfoʊkəl/
  • Specialized
: parfocal
  • Using parfocal eyepieces allows astronomers to seamlessly observe celestial objects at varying magnifications.

Examples

  • The parfocal objectives on the microscope allowed students to switch magnifications without losing focus.

  • The camera's parfocal zoom lens kept the subject sharp as I changed the focal length.

  • Using parfocal lenses saves time during laboratory work because you do not need to refocus each time.

  • The new camera lens is parfocal.

  • Is this lens parfocal?

  • Parfocal lenses make it easy to switch between different magnifications without needing to refocus.

  • This microscope has parfocal objectives, ensuring that specimens remain in focus when changing from low to high power.

Surface Forms

parfocal positive

Morphology

parfocal = focal (semi-transparent) = par + focal

Formed from 'par-' + 'focal' where 'focal' is clear but the prefix 'par-' (meaning 'equal'/'same') is not a productive or widely known English prefix, so learners may not reliably infer the meaning.

Etymology

Parfocal breaks into par and focal, where par is like the English word 'par', used in golf, meaning 'equal', and focal comes from focus meaning 'focus'. So, parfocal means 'equal focus' and describes lenses that stay in focus when you change magnification or zoom.