This exercise is part of the general project of what makes colour. Of the three qualities that make colour - hue,saturation and brightness - it is the last that is the subject of this exercise.
We needed to find a colour that would fill the frame - I chose a postbox - and then take five images, 2 successively underexposed, an average exposed image, and two overexposed. From darkest to lightest, the images appear as follows:
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| f6.7 1/180 EV-2 |
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| f5.6 1/125 EV-1 |
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| f4.5 1/90 EV0 |
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| f4.0 1/60 EV+1 |
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| f4.0 1/30 EV+2 |
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Rather than use aperture changes as suggested in the text, I adjusted the Exposure Value and P mode on the camera, letting it set the relative aperture and shutter speed settings. Depth of field is not an issue here.
My camera is set to half point increments so my images are taken at twice the range suggested in the notes; looking at the results, this seems a justified modification.
Looking at the results, we can see that the colour changes from a deep burgundy at the lowest exposure, through red (genuinely postbox red) at the average, almost to orange on the brightest image with intermediate stages between.
From this exercise, I learnt to respect exposure (and brightness) not just as factors in their own right, but also in a way that affects the colours in an image - the colours do not simply become brighter or darker, they actually change in pigmentation appearance. An important lesson in digital processing.
