effective sensitivity; functional sensitivity
Technical term used mainly in photography and imaging to describe the practical light sensitivity of a film or sensor, as opposed to its nominal rating.
The effective sensitivity of this film is equivalent to ISO 400.
With a digital camera, you can reduce noise by adjusting the effective sensitivity.
感度 is general sensitivity; 実効感度 specifically refers to the effective or functional sensitivity in practical use, often in photography.
ISO感度 is the standard ISO sensitivity rating; 実効感度 may differ from the nominal ISO value under certain conditions.
Compound of 実効 (effective, practical) and 感度 (sensitivity). The exact historical derivation is uncertain; the term is a modern technical coinage.