| Introduction | Testing lab | Noise & dynamic range | ISO sensitivity | Color sensitivity | MTF | Distortion, LCA, and vignetting | Light transmission |
Testing protocol for ISO sensitivity
The purpose of (saturation-based) ISO sensitivity measurement is to measure the exposure necessary to reach a given sensor's saturation point.
To measure the camera sensor’s ISO sensitivity, the camera body alone (without a lens) is set up on a stand to receive light from a controlled source. The source is positioned far enough away from the camera sensor to ensure good light uniformity on the sensor plane. The illuminance received by the sensor is precisely measured with a certified lux-meter.
The measurement protocol is modified if the camera has non-removable optics (as is the case with most DSC and bridges). To minimize the influence of the optics on ISO sensitivity and to avoid vignetting, measurements are performed at the image center. The camera is set up on a tripod to receive the light from the noise target with the center patch open. (The center patch luminance is measured with a certified luminance-meter.) ISO sensitivity is calculated as described here.
The sensor exposure is obtained by multiplying the illuminance by the exposure time. As there might be a slight difference between the exposure time announced by the manufacturer and the one used to take the shot, the sensor integration time is measured with a specifically-designed device consisting of a set of LEDs that are lit in sequence at a known, precisely-timed frequency. To perform the measurement, the number of lit LEDs is counted on an exposure taken with the camera.
Read more about ISO Sensitivity