My EOS camera has four metering modes: Evaluative, Partial, Spot and Centre-weighted. When do I use them?

Vanessa Gables, Kempston

BRIAN SAYS… In-camera exposure meters work by measuring the light reflected from the scene, so the subject colours and reflectivity affect the reliability of the meter. Handheld light meters are used to measure the light falling on the subject, termed incident light, and as such are not influenced by the subject.

EOS cameras use the Evaluative metering mode as their default, and it is a good choice for a huge range of subjects. Over the years, Evaluative metering systems have added colour sensing, and measure from more parts of the frame. Mirrorless cameras use the image sensor for exposure metering and this has made Evaluative metering even more consistent. If you are not sure which mode to use, use Evaluative as it does a good job for almost all pictures.

Partial and Spot metering both measure the reflected light from a small area at the centre of the frame. Spot metering measures from the smallest area, typically around 2% of the frame, and Partial covers around 10%. Using a custom function, EOS 1D series cameras can link the position of the spot meter with the AF point. This makes it really important to meter from an appropriate part of the scene that represents the mid-tone you want to achieve. Spot and Partial require a more considered approach – you need to plan where to meter from and likely use the exposure lock before taking your photo.

Centre-weighted measures from mostly the central part of the frame – larger than Spot or Partial – but tries to avoid including too much from the top to prevent erroneous readings caused by lighter skies.

Spot metering from a suitable section of the track before the cars arrive helps to ensure exposure consistency independent of the car colour

Evaluative metering was used here but any mode would work as brightness/tone are consistent