Knowing how your meter measures light allows you to manipulate and interpret the results and know when you need to change something.
Your histogram is one of the most valuable tools in explaining the tonal values of a scene. The far left represents pure black and the far right represents pure white. The horizontal axis is 0-255 and the vertical axis shows how many pixels are in each position of each tone.
The optimal histogram should not be too heavily bunched at either end of the horizontal axis, as this can cause the detail to be lost in the pure white or pure black. Ideally the histogram should look a bit like a bell curve, with a peak in the middle and starting/finishing in the far bottom corners. However, the ideal theory is not always able to be put into practice, often the light and shadows do not allow for us to expose for a perfect histogram. If you understand that a histogram to heavily bunched at either end of the horizontal axis can cause a loss of detail then you can look to manipulate the settings to allow for that clarity to still come through (changing ISO, white balance, shooting directly into the light, adding additional light to the scene).
Light metering is an additional tool to help prevent the loss of details in the pure white and pure blacks.
Spot Metering only evaluates the light around your focus point and ignores everything else. It evaluates a single zone/cell and calculates exposure based on that single area, nothing else. Spot metering works great for back-lit subjects.
Centre-weighted metering evaluates the light in the middle of the frame and its surroundings and ignores the corners. Use this mode when you want the camera to prioritize the middle of the frame, which works great for close-up portraits and relatively large subjects that are in the middle of the frame.
Matrix or Evaluative Metering mode is the default metering mode on most DSLRs. It divides the entire frame into multiple “zones”, which are then all analyzed on individual basis for light and dark tones. The metering system looks at where you focused within the frame and marks it more important than all other zones.
As with all photography, practice is the only way that you are going to improve and understand your camera more. Luckily with digital cameras there is no limit to the amount of images you can take and with there is an no limit to the subjects that you can capture as well.
Happy Snapping, CJeffers x