Project 11: the colour of daylight.

Interestingly this project appears to have no actual photography to carry out in order to complete it.  I find colour and its use in photography an interesting subject and have studied it on more than one occasion but there always seems to be more to learn.  I take 'Outdoor Photography' magazine every month and this month's edition includes an indepth article entitled 'Master the Power of Colour' written by regular contributor Pete Bridgewood.  Both this article and the course notes deal with the fact that white light is made up of the spectrum of colours, although Pete Bridgewood goes into more detail regarding how our eyes and brain actually perceive colour. I remember from school science and more latterly from Open University work the theory of the spectrum.  I love to find rainbows and a few years ago was delighted to be able to take this image of a stormy sky lit by sunlight from behind forming a magnificent rainbow, each individual raindrop acting as an individual prism to split the white light into its constituent colours.

Both the course material and the 'Outdoor Photography' article go into depth about colour temperature which I understand but the more one goes into it the less intuitive it becomes. Although the highest temperature of 7000K is for a clear blue sky, we tend to think of colours at this end as cool colours and, conversely, 3000K is the colour temperature of a sunset, the oranges and reds of which, we tend to refer to as warm colours.  This is made even more complicated with Raw conversion software such as Adobe Lightroom which I use.  When  the colour temperature slider is moved over to a lower colour temperature, more towards what we know as the temperature associated with more orange light - the image becomes more blue.  This is because the colour temperature slider is actually a colour temperature compensation slider.  So, when we move it to the left we are giving an instruction to the software to compensate for the fact that we were lighting the image with light of a low (orange) colour temperature.  The software then displays the image after giving a blue correction to compensate for the original orange light, eg tungsten.  I have had to deal with this in the reverse when responding to my tutor's comments on my first assignment.  It was felt that some of my images were too blue so I needed to move the slider to the right to 'warm' them up slightly.  Of course with digital cameras it is possible to set a white balance for the particular conditions experienced, although with Raw images the white balance can be corrected during post processing.

Measuring Light

In my early days of film cameras, when I owned a non metering Zenith, I remember using a light meter reflectively quite successfully.  I never got into the realms of taking incident light readings.  I am used, over many years now, to using built in metering with my cameras.  I work with canon 7D and 50D bodies and rarely if ever set them to auto.  I generally use aperture priority metering.  Both cameras have spot metering so if necessary I can fall back on this rather than my normal evaluative metering.  I tend to use spot metering in difficult light situations (perhaps very contrasty) when I want to ensure that the main part of the image is correctly exposed - a bird, insect of flower for instance.  I am also in the habit of employing exposure compensation in difficult lighting conditions - a snowy scene, perhaps, or a bird in flight against a bright sky both need some positive exposure compensation.  I 'normal' lighting conditions I routinely dial in 1/3 or 2/3 negative compensation to ensure rich saturated colours much as Galen Rowell used to underrate his Kodachrome films.  I do find it important, though, to regularly check the histogram and adjust the compensation accordingly.