Underexposed vs Overexposed Photos: Which is Worse?

Proper exposure is one of the trickiest things to get right in photography. There are so many factors within the camera that can affect the exposure, and it all depends on the lighting and whether the subject is moving. Shutter speed, ISO sensitivity, f-stop, all of these things affect exposure and can make the difference between a great shot and a worthless shot. 
 
The easiest and best way to ensure that you get a proper exposure is by bracketing. Take multiple photos of the same subject under the same conditions, changing settings like f-stop and shutter speed with each shot. Out of the pile of photos you get, at least one of them should look good. Many cameras offer automatic bracketing, which lets users cycle through a range of exposure values with the touch of a button, removing the need to go menu-diving for each shot. 

Of course, you can't always bracket, and eventually you're going to have to decide whether you want to err on the side of overexposure or underexposure for a shot.
 
Neither case is ideal, but thanks to Photoshop and working with raw image files, users can work wonders with slightly-off exposures.  
 
In either case, you can fix at least some of the problems from the off exposure by shooting in RAW and editing the image in Adobe Camera Raw or other image processing software. By manipulating exposure and, in the case of underexposure, recovery and fill lighting, you can bring the subject back from the depths of darkness and the wastelands of blown-out light.  
 
In general, strictly based on how the image will look after you "fix" it, it's better to overexpose a photo than underexpose it. By reducing the exposure, the final picture might have some skewed or muddled colors, but everything in frame will at least appear sharp. Even if the photo looks completely blown out, you can pull down the exposure to produce an at least somewhat usable picture. 


Underexposed photos, on the other hand, can be a nightmare to fix. By pushing up the exposure, you're bringing out every last stray bit of light the camera caught. This appears as noise in the photo, and even if the adjustments bring your subject out of the shadows, it still ends up a fuzzy, grainy mess. There are many steps you can take to reduce noise, but it just adds another layer of work to the process of making a picture acceptable, and it peels off even more detail from the original image. 
 
Overexposure isn't always and option, and sometimes you'll have to settle for underexposure. If you're taking photos at a concert or a night club, the lights will be low or the subjects will be moving, and you simply won't be able to get a decent exposure, and you certainly won't be able to overexpose. In those cases, you'll simply be resigned to underexposure. The best way to limit the damage to the picture is to maximize the ISO sensitivity and use the widest f-stop your lens can reach. You'll still have to deal with graininess, but it won't be quite as bad as it would be otherwise. Just be sure to watch your shutter speed; no post-processing can fix a blurry, moving subject. It's better for the final picture to be noisy than completely unusable. 

Above all else, remember that you can only fix the image data that your camera's sensor retains. Whether you overexpose or underexpose, going too far in either direction will result in an image no photographer can fix afterward. An image that's too underexposed simply doesn't pick up any of the light reflected by the subject, and an image that's too overexposed completely blows out the subject with light, eliminating all the details. 
 
Lead image credit: Flickr user Garryknight