Ｆ値えふち

noun

f-number; f-stop; focal ratio

Technical term in photography and optics for the ratio of the lens's focal length to the diameter of the entrance pupil. Often written as 'F値' or 'f値'.

• このレンズのＦ値えふちは2.8です。

  The f-number of this lens is 2.8.

• Ｆ値えふちを小ちいさくすると、背はい景けいがぼけやすくなります。

  If you make the f-number smaller, the background becomes more blurred.