Exposure essentials
Q My photography is plagued with poor exposures. What should I be doing to stop this happening? Tom Smith
Andrew says You don’t say whether you are over- or underexposing – so I am going to assume that it’s a combination of both evils! Getting an exposure correct (or as correct as it can be) is one of the fundamentals of good photography. If you constantly get exposures wrong, you really need start checking everything as you take a shot and employing corrective measures.
For starters, use your histogram more. When you take a photo, review both the image and the histogram that’s also available to study. A histogram is basically a graph that arranges the pixels in the image in order of their tonal depth. What we are concerned with here is what the histogram can tell us from either the left side (shadows) or the right side (highlights).
If the image’s graph shows the pixels are clipping to either the left or the right, we know that the image will be likely be wrongly exposed, and you need to dial in more or less exposure via either shutter speed or aperture. This isn’t unusual: a scene is rarely tonally balanced, so the camera’s meter is frequently fooled into making the image too dark or light. For example, if a scene is predominantly light, it may think the whole scene is actually lighter than it is and consequently underexpose it. In these circumstances, we need to dial in extra exposure to get it right. This is called exposure compensation: if you use it regularly, you’ll start to understand what can fool the camera’s meter, and compensate for it as you shoot.
Incidentally, if your main problem is overexposure, you should also enable your camera’s highlight alert warning. It will blink at you whenever you burn out the highlights, and can act as a useful first indication of exposure problems.