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Today's question is: "Is it better to under expose or over expose an image?" This is a great question. There is a lot of theories buzzing the web saying we should underexpose our shots by a stop or so. Let me begin by saying our supreme goal must be to nail our exposure. In fact, get a good exposure, listen carefully, and you might just hear angels singing.
Back in the slide film days, it was better to underexpose your shots. Though the frame would be a bit dark, you still had detail to work with. But if you overexposed it, the detail was lost. It was therefore common to underexpose your film by a half a stop or so, just to be on the safe side. This practice has carried over into the digital realm.
When shooting with a digital camera (particularly in JPEG), you have a small margin of error, much like slide film. Many photographers, therefore, adopted the practice of underexposing their shots, hoping to play it safe. But here’s the problem…in digital, if an image is underexposed, there are more dark areas in the image. Noise is most prevalent in the shadows. Annnnd if you lighten a dark image, you’ll be lightening the noise in the image. Then, when you get it to the proper exposure, will it look, well, noisy. On the other hand, if you overexpose the image, there is less noise recorded. Then when you darken it, you won’t be adding any noise, and the image will look cleaner. Therefore, if for some reason can’t nail the exposure dead on, and you have the choice, choose to overexpose the image. The end result will be much better. But again, the goal should always be to nail the exposure in camera.
Here’s a fun little exercise. To see the difference, try it out. Shooting in RAW, take two shots of the same scene. In the first, underexpose the shot by a stop or two. Then bring it back up when you process it. You’ll see how the noise in the shadows shows up as you lighten the image. In the second shot, overexpose the image just to the point of blowing out the highlights. Then bring it back down when you process the file. You’ll be amazed how clean your image is.
I must disagree with you when you say that it is better to overexpose than underexpose. If the situation arises where you cannot get an accurate exposure and you cannot shoot multiples and combine them together in Photoshop, I much prefer to underexpose (as long as it is no more than a stop to a stop and a half under) than to overexpose. The reason I say this is with the technology in the cameras and in Photoshop it is much easier to remove/reduce noise than it is to try to burn in or add detail to a detail-less area that has been blown out. If you try to burn in a blown-out area, all you will get are gray highlights. I would rather have something data wise (even if it is grainy) to work with than sacrifice all my highlight details when I shoot and not have anything to work with in post.
ReplyDeleteWhether or not I over or under expose really relies on the subject. For people, I actually like to overexpose by half a stop for their skin tones. But I have to agree with Stephen. I would much more rather have noise than a loss of detail, especially in my black and white work. And I just love grain! :D
ReplyDeleteStephen: I actually agree with you. If the detail is lost, it is lost. I thnk we are talking about two different things. My premise was never to overexpose to the point of lost detail. Both extremes are terrible -lost highlight detail and blocked up shadows. But if you overexpose an image, and haven't lost detail, then it is cleaner once you've corrected it in post, than if you underexpose without loosing detail, and bring up the shadows. Given you still have detail in an overexposed highlight, when you correct it in post, you won't be adding or amplifying noise. However, if you have detail in inderexposed shadows, you amplify the noise when you lighten that area. If you haven't blown your highlights or blocked up your shadows, its simply cleaner to work from an overexposed image than an underexposed one.
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