HDR photography attempts to capture subject contrast which can’t be covered by a single exposure through the use of several recordings of varying exposure, after which the images are totalized with the help of software so that areas within a recording without image information (detail) are replaced by variously exposed recordings within which these areas do demonstrate detail.
If subject contrast is measured with the external exposure meter, two f-stops (min, max.) are obtained as an initial value or image exposure. If the exposure meter also provides the average value (avg.), we already have three values. The min. value corresponds to exposure of the shadows and the max. value to exposure of the bright areas. Other exposures can then be obtained by stopping up or down.
Handheld exposure meters can be used to ascertain subject contrast by means of the reflected light metering method. While pressing and holding the measurement key, the exposure meter is pointed at the various brightness values, one after the other, or scans the entire subject. Some simpler models then either display the f-stop range (smallest to largest f-stop) or the exposure value difference (EV, f-stops) is directly displayed and the minimum, average and maximum values, as well as the associated f-stop / shutter speed combinations, can also be queried – ideal initial values for HDR photography or for adjustment to the contrast range of the image recording medium.
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