What Are Parfocal Eyepieces?

A parfocal lens is a lens that stays in focus when magnification/focal length is changed. There is inevitably some amount of focus error, but too small to be considered significant.

What does parfocal mean on a microscope?

Parfocal means that the microscope is binocular. ... Parfocal means that when one objective lens is in focus, then the other objectives will also be in focus.

What does a parfocal lens do?

A parfocal lens is a lens that remains in focus even as the magnification or focal length changes. Parfocal lenses allow the user to zoom in on a subject and zoom back out while maintaining the same focus. Parfocal zoom lenses are not just used in photography: they are also common in microscopes and telescopes.