Do you take multiple photos of amazing subjects, only to find when you transfer them to your computer screen that they look dark with indistinguishable details? These images could be underexposed.
Underexposed photos are those that appear too dark, with only the brightest components of the photograph easy to make out.
So how do you correct this common DSLR problem?
How Under Exposure Works
Your DSLR camera comes with exposure metering, which measures reflected light from the subject to determine the best exposure for any given image. These days, exposure metering systems are sophisticated, with multiple options available for different shots.
But it doesn’t matter how advanced your camera’s meter is, it can still get the exposure wrong. It works by averaging out all the tones in a scene to a mid-grey tone.
So if your scene has plenty of light tones or a large area of light colour, your camera will try to find an average mid-tone. Likely, it will render those brighter tones grey and underexpose your photo by up to two stops.
The best way to see whether your image is underexposed is to look at the histogram. This is a bar graph that shows the pixels exposed in your image; the left side represents black shades and shadows, the right-side highlights and brighter shades, and the middle section the grey tones.
For photographs where the subjects are lighter tones, the bar graph should have heavy representation on the right-hand side of the histogram.
How to Fix Under Exposure with Your DSLR
Too many photographers think that they can ignore their exposure settings until they get to post-production. But it’s important to get exposure right when you’re taking the picture.
The reason for this is that to brighten an underexposed photograph in a post-processing program, you’ll lose a lot of the shadow detail and will likely increase the amount of noise in the image.
Use Your Exposure Compensation Function
The exposure compensation function on your DSLR is the easiest way for you to fix underexposure while you’re taking the shot.
You can use this function if you’re shooting in the Program, Aperture Priority, or Shutter Priority modes. You can simply dial up the exposure setting a stop or two to compensate for brighter subjects.
Each brand operates the exposure compensation mode in a slightly different way, so be sure to check your brand’s manual for full instructions.
Use Centre-Weighted Metering for Back-Lit Subjects
Sometimes, you’ll get underexposed images when your subject is either backlit or darker than its surroundings. It occurs because your camera is trying to balance out the entire exposure across the image.
In this case, switch your metering to centre-weighted mode. This instructs your camera to pay special attention to the centre of the image, better exposing your subject.
If your DSLR comes with a spot-metering mode, you can also use this option, helping you to correctly expose a subject that may not necessarily be in the centre of your image.
Use an ND Filter for Contrasting Landscape Shots
Landscape photographers will be familiar with the issue of underexposed foregrounds when there’s a bright sky in the scene. Once again, your camera is trying to figure out a mid-way tone for the whole image to correct the contrasts.
A neutral density (ND) filter is a great way to correct this problem. Half of this filter is dark, while the other half is clear. You can place the dark half over the sky, and leave the clear part for the foreground, helping to balance out the brightness contrast.
ND filters normally come in a range of different f-stop ratios, signifying how much darker the dark part of the filter is than the clear part
Underexposure can seem like a big problem for many photographers – but once you better understand how camera exposure works, it’s not difficult to troubleshoot this problem and find easy solutions.
For more photography tips and advice, be sure to check out our other advice articles on the Camera House blog today!
