The aperture size (area of the aperture) of a lens could be calculated from focal length and the correspondent f-number.

光圈孔的大小，可从镜头的焦距与焦距比数中计算出来。

youdao

The aperture size (area of the aperture) of a lens could be calculated from focal length and the correspondent f-number.

光圈孔的大小，可从镜头的焦距与焦距比数中计算出来。

youdao