The thing I found trickiest about this exercise was not the photographic aspects but the basic ICT bits. I took 3 sets of photographs, checking the histogram as I went, opened them in Elements, examined them, took a screen shot of each and saved it with the histogram but the only way I could think to do this was in a word document. Although I can insert them into this post, they are included as documents rather than images so although people can click on the link if they want to look at them, they can’t just see them at a glance. Another issue was that I needed to make sure that the highlight and shadow clipping warning was displayed which meant that I had to inspect and save the images as they were shot without being processed, in this case in RAW, which makes me wonder if I’m jumping ahead of myself shooting in RAW at this stage.
As far as the images themselves are concerned, I’m not sure I got that quite right. For the ‘flat’ image I chose a garden of red poppies believing that the tonal range was pretty even across the board. Rather than this resulting in the values in the histogram being squeezed to one side or the other, they are spread across the whole width of the histogram but the peaks and troughs in the histogram are all quite flat. Shadow clipping is easily seen, at least in the second and third shot and the histogram does show highlight clipping too but this is less easy to see because this shows up as red, the same colour as the poppies, argh, definitely not the right choise of subject!! Click here for Low contrast shots.
In terms of the images themselves, the 3 shots were taken at +.67, 0 and -.67 exposure compensation, so not the 1 stop as suggested in the exercise and although you can clearly see differences in the highlight and shadow clipping warnings, the histograms themselves are not all that different in Adobe Camera RAW although to my mind they looked very different when viewed on the camera with the first 2 shots looking quite over exposed.
The second subject was a group of terracotta cloches in the same garden. I chose those because I felt that the contrast was average with a good range of dark, light and medium tones. Again the photographs were taken at -.67, 0 and +.67 exposure compensation. In all three shots there was clear evidence on highlight clipping with a little shadow clipping in the second and third image. Although the histograms do not vary greatly from one image to the next, in the second and third images, the values are slightly more weighted to the left. Click here for Average range shots.
For my third subject I chose a pale blossom against a dark green background, and on inspection actually felt that this probably worked best of all the subjects chosen. The values on the histogram are spread right across the width but the bulk is very much to the left and although highlight clipping warnings are evident in the first two, shadow clipping warnings are very evident in all of the images. Click here for High contrast shots.
One of the things I found quite interesting about all of these sets of images was that when I came to process the RAW files, I got better results by selecting the under exposed image and moving the black slider to the left to reduce the shadow clipping than I did but reducing the exposure on the over exposed images. Each of the following images was the one taken with -.67 exposure compensation and on reflection I really need to do this exercise again with at least 1 stop between each exposure and with a better subject for the low contrast image.
Once the images had been processed in RAW and opened in Elements, the histogram looked completely different depending on which colour channel I chose. I feel as though I have got the hang of the horizontal element of histograms but I still don’t understand what to do to control the vertical element. Something else I need to research further!