Translation guide
The f-number (or f-stop) is a measure of lens aperture in photography. In Japanese, it is expressed using katakana or the letter F followed by the number.
F値はいくつですか？
What is the f-number?
Expressing the aperture value of a camera lens
The standard term for f-number in Japanese. 'F' is pronounced エフ, and 値 means 'value'. Used in technical and everyday contexts.
このレンズのF値は2.8です。
The f-number of this lens is 2.8.
F値が小さいほど、背景がぼけやすくなります。
The smaller the f-number, the easier it is to blur the background.
A direct loan from English, used in some technical contexts. Less common than F値.
In Japanese, f-numbers are typically written with a capital 'F' followed by the number, e.g., F2.8. The slash notation (f/2.8) is less common but understood. When speaking, say エフ (F) and then the number.
Fナンバーが小さいレンズは高価です。
Lenses with small f-numbers are expensive.
Literally 'aperture value'. Sometimes used interchangeably with F値, but can also refer to the physical aperture diameter. More common in technical manuals.
絞り値を変えて露出を調整します。
Adjust the exposure by changing the aperture value.