Exercise: Control the strength of a colour
Find a strong, definite colour and fill the frame with it. Find the average exposure setting with the cameras meter, or hand-held meter, and take five pictures on manual setting at 1/2 stop intervals from the metered normal, two above and two below normal. Apart from the obvious over and under exposure what other difference is there in terms of the colour?
As the exercise was supposed to show, the obvious difference is the under and over-exposure from the norm. I’m not sure what anyone else found who did this exercise, but I’m not used to distinguishing between brightness and saturation as a mental process and so I’ve previously termed them one and the same. After reading the notes with this exercise I now realise the difference and know that saturation is how deep the colour is, or as I prefer to think of it, the density of a colour and that brightness is the amount of light, from very dull to very bright, that the colour is.
In this exercise the saturation remains constant, hue is constant but the brightness changes, as would be expected by changing the size of the aperture whilst the shutter speed remains fixed, thus allowing more or less light to strike the sensor and thereby changing the brightness of the captured image.
One of the things I’d been puzzled about for some time with my photographs was the fact that in any given series there sometimes appeared to be a shift in colour of say grass or other mono-coloured areas. I’d tried to work out what the meaning was and could only surmise that this was because of the changing aspect of each shot and slightly differing light conditions, which in some ways I suppose was correct. However I now realise that the true cause of the colour shifts was due to the changing of aperture and shutter speed changing the brightness of the image and with that knowledge I can hopefully control that situation for more consistent results.