Metering light.

The opening notes of this module remind us of the nature of light, the possibilities and the importance of understanding what can be achieved if we master the art of exposure.

As covered in the last module I know that white light is made up of three colours of light being red, green and blue. (The different proportions of the R, G and B give us the light temperature.)

Several years ago, when I first started out with photography I learnt the art of balancing aperture and shutter speed based on depth of field required and the overall effect desired.  Also I have increased my ability in managing dynamic range ( maintaining  detail in highlights and dark shadows) by learning how to read histograms and applying different techniques with grad filters.  However, revision is never a bad thing and I am sure there are gaps in my knowledge that need to be addressed.  This can be a very scientific subject. I am no scientist  though so I aim to understand as much as I need to achieve without being too snowed under with the science.

In the course notes, the point is made that we need to make a decision when we look through the view finder if we want a scene to be average, lighter or darker. This project aims to help us explore the possibilities by controlling metering and exposure.  Admittedly, up to this point, I aim for averaging everything and adjusting in edit to the desired effect. Or, in situations of high dynamic range, I expose for the highlights and lift shadow in edit.

There are two ways of measuring light:

– Incidental light which is light that falls on to a scene and requires a hand held light meter to measure.

– Reflective light that is, as you might gather, light that reflects from a scene.  A camera’s inbuilt meter measures this.

This is something I have been aware of for a long while but is reinforced in ‘Cambridge in Colour’.  It was good to revise the issues in  metering though and brush up on knowledge. I am aware too that there can be flaws in this ‘in camera’ metering. The system requires light to be reflected as an average equivalent of c.18% grey and in certain situations, such as in snow, light isn’t reflected as 18% and the exposure will be incorrect as a result  (

In our notes I read that a camera has 3 metering options and these are:

  • Spot metering. ( Analyses a small area and measurement taken from focal point.)
  • Centre weighted metering. (Commonly used for average metering across the scene but priority to the centre)
  • Matrix / Partial metering. (Analyses a larger area and useful in situations where the background is brighter then the subject.)

I am aware of these metering options but, if I am honest, I haven’t really experimented with these different metering options as much as I could have done and will explore these exercises with some interest, as here might be the key to greater creativity in outcomes.

Some useful advice is to use exposure compensation in ‘difficult’ reflective lighting conditions. i.e.  +1 for snow (although to avoid clipping highlights it might be worth the under exposure to correct in post production) and – 1 for dark situations.  (

To conclude it is good to be aware of the camera’s capabilities and experiment with them while being mindful that every situation renders it’s own unique challenges.  I look forward to experimenting in the first exercises in this module.

Unknown. (2013). Camera Metering. Available: Last accessed 22/01/2014.

Exercise link:


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