Control the strength of a colour

Colour is to be the topic of the third part of The Art of Photography. Due to it’s now ubiquitous use in photography (after it’s history is in the main made up of black and white photography), colour and it’s constituent make-up is often overlooked. The fact is that, in order to understand what we see, we also need to understand how the camera sees colour and how our eyes interpret it. It will be interesting to see how intuitive my use of colour is as it can be a very in-depth subject should one choose to pursue it. This section of the module will set out to understand more about the three uses of colour in photography; the visual, the expressive and the symbolic. This exercise will demonstrate how to control the colour strength by changing the exposure of a photograph.

I was to take five photographs of the same subject. I was looking for a solid and dominant colour within the frame so that I could adjust the exposure by half-a-stop at a time. I was shooting in manual mode to give me the same shutter speed while I adjusted the aperture. The initial photograph was taken using the settings given to me by the camera’s inbuilt exposure meter (centre-weighted in this case). This gave a good average exposure to start from (and is the middle image of the series). Then I took two other photographs either side of this start point, increasing by two half-stops one side and decreasing by two half-stops the other. This amounted to a stop brighter and a stop darker than the original image with a half-stop in between. Effectively this left me with two over-exposed images and two under-exposed. The following photographs are shown in order of f-stop and I will describe what I see in each.

Under-exposed - ISO200, f/7.1, 1/50, 82mm

Under-exposed – ISO200, f/7.1, 1/50, 82mm

This brown door gave a very solid colour that also gave the viewer a modicum of interest. It was also very easy to expose for with the centre-weighted meter. What was a very regulation brown to my eyes now has a warm orange feel to it, heading towards yellow in the colour wheel.

Over-exposed - ISO200, f/8, 1/50, 55mm

Over-exposed – ISO200, f/8, 1/50, 55mm

Stopping down half-a-stop produces an already richer colour in comparison to my first image. The image starts to head the opposite way in the colour wheel towards red.

Centre-weighted exposure - ISO200, f/9, 1/50, 82mm

Centre-weighted exposure – ISO200, f/9, 1/50, 82mm

This is my ‘average’ exposed image, which was my benchmark for the other shots. In comparison to how I saw (my eyes perceived) the colour, this is not very close. The door was much darker. In theory, this should be the image that is ‘correct’. However, as just explained, I don’t think this is a true representation of the colour I had in front of me.

Over-exposed - ISO200, f/10, 1/50, 82mm

Over-exposed – ISO200, f/10, 1/50, 82mm

Stopping down by half-a-stop again increases the apparent darkness in colour, getting closer to what I saw at the time.

Over-exposed - ISO200, f/11, 1/50, 82mm

Over-exposed – ISO200, f/11, 1/50, 82mm

This image is stopped down one full-stop from my start point (f/9). This image probably gets closest in the series to a true representation of what I saw. In theory, it is over-exposed but the darker brown gives a perceived diference in richness to the colour.

The results are not entirely surprising for a number of reasons. The human eye is extremely clever and adjusts to the environment it is asked to work in. In reality, I never got close to filling my own field of view with just the door. I had external influences on my vision such as other colours, contrasts and very bright sunlight. These would all combine to make my perception of the door a certain colour and perceived saturation. If the lighting, for example, had been different then I would have perceived the colour differently. In respect of the camera it could be that my camera has a tendency to under-expose when shooting and needs to be adjusted accordingly. However, the main contributing factor to the difference between my eyes perception and my camera’s recording is just that. My eyes perceive, my camera records. All I have asked my camera to take in to account is the brown expanse in the frame, nothing else. It has recorded exactly what I have asked it to in purely physical and mathematical terms. For it to record anything else would be impossible.

It is worth noting that all I have done here is change the exposure i.e. the brightness of the image; the colour and hue remain the same as I cannot change the physical reflective attributes of the object merely by changing my aperture. Our eyes only perceive a colour or saturation change and in part this is only due to the fact we have all the images lined up to compare.

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