Digital camera tips: 27. Spot the midtoneWhile your camera’s multi-zone metering mode (aka Matrix or Evaluative) will deal with most scenes, a Partial or Spot metering pattern can also be invaluable when you’re shooting in mostly bright or mostly dark situations, when you can use it to take a reading from a nearby midtone, such as a pavement or grass.
Digital camera tips: 28. Assess the contrast
As well as enabling you to take a precise meter reading, you can use your camera’s Spot meter to determine the contrast in a scene. Take one reading for the brightest highlight area, and another for the deepest shadow to determine how many stops separate the two readings. If this exceeds your camera’s dynamic range, you’ll have to accept some clipping in the shadows, highlights, or both, or consider shooting a bracketed sequence for an HDR (High Dynamic Range) shot.