Photographic sensitivity

Japanese: 写真感度 - しゃしんかんど（英語表記）photographic sensitivity

It is sometimes called photosensitivity or simply speed. It refers to the degree to which a photographic material is sensitive to light or radiation. Photographic film and paper are produced by coating a support with a photographic emulsion, in which photosensitive silver halide is dispersed in gelatin, and then drying it. The sensitivity of photographic materials varies greatly depending on the manufacturing method of the photographic emulsion and the type of compound added to the emulsion. Negative films for general photography have a high sensitivity, while copying films and photographic paper have a low sensitivity. The photographic sensitivity of general photography films is expressed as a single number and is used as a guide to determine the exposure conditions for photography.

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

感光度，あるいは単に感度ということもある。写真感光材料が光や放射線に対して感光する度合をいう。写真のフィルムおよび印画紙は，感光性のハロゲン化銀をゼラチン中に分散した写真乳剤を支持体に塗布し乾燥して製造する。写真乳剤の製造方法や乳剤に添加する化合物の種類によって写真感光材料の感度が大きく異なる。一般撮影用ネガフィルムは感度が高く，複写用フィルムや印画紙は感度が低い。一般撮影用フィルムの写真感度は一つの数値で表して撮影の露出条件を決める目安として使われる。

出典　株式会社平凡社世界大百科事典第２版について　情報

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