Digital camera light meter calibration

RawDigger. Exposure meter calibration

Unlike film sensitivity, which can be measured using a standard procedure, the sensitivity of a digital camera is somewhat a fuzzy concept.

Moreover, the sensitivity of the camera turns out to be a pretty random variable, and the camera manufacturers do not make it easier for the user, adding quirks of their own.

Further on we will discuss a simple method, which allows us to calibrate the exposure meter in such a way that on different cameras (or on different sensitivity settings of the same camera) the results are predictable.

Determining pixel charge capacity and amplification gains for a digital camera

Unlike its film-using predecessors, modern digital cameras present us with a challenge of a non-replaceable sensor. Due to this, the given amount of light, which falls on an element of the sensor (pixel), creates the same charge irrespective of ISO sensitivity setting resulting in an identical output signal. The response of the sensor itself depends only on the light, and not on the digital camera sensitivity (ISO) setting.

It would seem that this contradicts everyday photographic practices: if there is not much light, you have to set the sensitivity (ISO value) higher, and the picture will come out right, but if you set the sensitivity low, then it won t come out right. Lets have a closer look.


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