Exposure index

The exposure index is in the photo technique, a unitless numerical value that is inversely proportional to the photographic exposure of an image sensor is: ${\displaystyle S_{i}}$ ${\displaystyle H_{v}}$

${\displaystyle S_{i}={\frac {10\,{\text{lx s}}}{H_{v}}}}$

The reference value for the exposure ratio is 10 lux seconds .

The maximum exposure index at which an acceptable image quality can be achieved is usually as in photographic film as ISO sensitivity specified.

In the case of series of images that were taken with different exposure indices, we speak of exposure series .

Digital images

Digital cameras do not need in which, by the properties of the hardware specified by the manufacturer or recommended exposure index (English: recommended exposure index (REI) ) are operated. The higher the set value, the higher the apparent sensitivity in the digital images (for example in a JPEG file). As a rule , the higher the exposure index, the worse the image quality of a digital camera .

The specific exposure index, which is required to produce a specified operated under the ISO 12232 conditions digital output signal is standard output sensitivity (English: standard output sensitivity (SOS) ) called.

The actual measured values ​​of the image sensors are recorded in the raw data of a photographed raster graphic . If the camera in question does not have any options for electronic amplification (or weakening) of light signals, the possible setting and recording of an exposure index in the metadata of these recordings (see for example under Exchangeable Image File Format ) only has a documenting character and has no influence on the saved ones Image data.

However, depending on the combination of exposure index and exposure compensation value , camera firmware can register the same amounts of light , but under certain circumstances produce completely different image results.

Web links

• DIN ISO 12231: 2017: Photography - Electronic still cameras - Terms
• ISO 12232: 2006: Photography - Digital still cameras - Determination of exposure index, ISO speed ratings, standard output sensitivity, and recommended exposure index

Individual evidence

1. ↑ ^{a b} DIN ISO 12231: 2017, photography - electronic still cameras - terms, 3.51 exposure index.
2. ↑ DIN ISO 12231: 2017, Photography - Electronic still cameras - Terms, 3.53 exposure series.
3. ↑ ^{a b} DIN ISO 12231: 2017, Photography - Electronic still cameras - Terms, 3.88 ISO sensitivity
4. ↑ ISO 12232, Photography - Digital still cameras - Determination of exposure index, ISO speed ratings, standard output sensitivity, and recommended exposure index.
5. ↑ ISO , Sony Europe, 2014, accessed July 26, 2017
6. ↑ Richard Butler: Canon 6D Mark II dynamic range falls behind modern APS-C cameras - ISO invariance , dpreview.com from July 20, 2017, accessed on July 26, 2017