Numerical aperture

The Numerical Aperture (NA) describes the amount of light coming from the focus that the objective can collect.

The NA depends on the half angle of the maximum cone of light that can enter or exit the lens. It is directly linked to the resolution of the objective.

Usually, the NA can be found engraved on the objective next to the magnification.

Note

Depending on the selected file format this parameter may be skipped, as explained in Import metadata.