Determining optimal exposure with RAW files
As there is less tonal information captured in the deepest shadows by a linear recording device such as a sensor, it is beneficial to overexpose at the time of capture ensuring as many pixels saturate as possible. This widens the range of tones captured and also helps to lessen noise and maximize color accuracy. Determining the optimal exposure for your camera, however, depends on the sensor’s dynamic range.
As a guide, you should ensure the histogram is as close to the right-hand side as possible without any of the channels touching or displaying a spike against the edge or wall of the panel. In addition, the histogram’s meter value located below. Sensors with the best dynamic range will tolerate the most overexposure, however, it is still expected that the optimal exposure for the majority of modern cameras will fall between ±0 and +0.5 stops mark, depending on the sensor’s capabilities.
Note that testing of the sensor to determine its characteristics should be performed prior to any critical work. You can confirm the exposure using the histogram in the Histogram panel in the Exposure tool tab - it should similarly be as close to the right-hand side as possible, without any of the channels displaying a spike against the edge or wall. Decrease the exposure by using higher shutter speed or by closing down the aperture.
Determining optimal exposure with RGB files
JPEG files are already processed to some degree, whether that is out of the camera or from Capture One (or another third-party editor). Therefore the histogram in the Exposure Evaluation panel is likely to be no different from that found in the Histogram panel. TIFF files may also be previously processed. This can be confirmed by assessing the two histograms.