Showing the correct exposure, then one stop under exposed, and then one stop over-exposed. The histogram shifts left towards black with under-exposure, and then to the right with over-exposure. There is an incomplete dynamic range with low contrast shots so the subject and exposure need careful consideration at the time of shooting, whereas is there is more latitude with average or high contrast shots.
This shot actually recovered in photoshop but my task now is to understand what I’ve left out.
With the average contrast shots the histogram has more values distributed across the range so when the exposure changes all the tones show a corresponding shift. Both ends move closer to clipping than the changes in the low contrast shot, but in this case they just stop short.
A high contrast shot at the correct exposure may show severe clipping, so when the exposure is over or under then the potential for problems is much greater than with average or low contrast shots. However because there is a high value in the brightness towards both the 0 and 255 ends of the scale, potentially there is more material to work with in combining shots to produce an image that has a wider dynamic range than the camera sensor. There is then judgement required so that the final image does not start to look unnatural as can happen using HDR software.
This is a useful exercise to show the relationship between contrast and clipping. I was familiar with the principles, although I referred to Michael Freeman’s book “Perfect Exposure”, and that actually confused me since it seemed to indicate that low vs average vs high contrast was indicated by the centre of the histogram. I need to read the rest of the book over the coming months.