This week let’s dive into this deceptively simple topic. Bracketing is when you take three or more pictures of the same subject in an attempt to hedge your bets. For example you might take one picture with your light meter dead center and the other two slightly under- and over-exposed.
There are two things about bracketing that are often misunderstood. The first is that bracketing involves only adjusting exposure. While this is the most common variable that is bracketed for, it’s by no means the only one. Basically, you can bracket anything you vary during shooting. I often bracket for depth of field when I am in aperture priority mode, for example. More on this below.
The second is the myth that with digital it is no longer necessary to bracket. After all, modern photo processing software allows you to change what you need to change rather easily. While this is true, it is also the wrong attitude to take.
You may choose not to bracket, but don’t do it because you think you can make the adjustment later on your computer. This is a road you don’t want to go down. Pretty soon you’ll be taking all sorts of short-cuts during capture, simply because you can “fix it in post”. There are simply too many advantages to risk not getting your exposure (or aperture, etc.) the exact way you want it before doing any post-processing. In fact, with digital there is every reason to bracket: you aren’t paying for film!
Let’s take one example. You are shooting a high-contrast landscape, into a low sun. You want to use just a single capture, so you slap a 2-stop graduated neutral density over the lens to bring the bright sky under control. If you bracket exposure (by shooting three shots, one with no exposure compensation, one underexposed by a stop and one overexposed by a stop), you end up with captures that vary in foreground brightness.
The sky, of course, will vary in brightness across your bracketed exposures too. You will hopefully have one with no blinkies (the highlight warning that tells you that part is overexposed) to one that has limited areas blinking. Later you might choose any of them based on factors such as how deep you want the shadows to be, and how much noise you can accept in the shadowed areas. You’ll need to balance that with how easy it is to bring down the highlights in the sky via your software. You have a lot more options if you have bracketed exposure.
Bear in mind you normally want to start with a slightly brighter image and bring your brightness down in post-processing. If you do the opposite, always doing a lot of shadow-fill to brighten darker areas of your image, you will end up with noise. Then you’ll need to either do significant noise reduction (which softens the image) or leave the dark areas darker than you wish, to hide the noise. Bracketing for exposure will allow you to evaluate your choices using your bigger computer display at home, which also has a better histogram. The image on your camera’s LCD is obviously not as good, and the histogram accessible on your camera is not as accurate as well.
There is another advantage to bracketing for exposure. Even if (like me) you will process the image as a single capture, trying to keep things as simple as possible, you still might want the option to combine multiple exposures later. For example, when you are better at Photoshop or if you get an image that is so great that it’s worth more work, you might want to try hand-blending multiple exposures, layered together in Photoshop. This can result in an image with more pleasing tones and contrasts. If you have the multiple captures, you have the option. It’s like having that extra sweater in your backpack on a hike. You might not wear it but if you need it you’ll be very happy you had the foresight to bring it along.
Let’s take another example. You are shooting macro images of flowers and insects. If you bracket for aperture your chances of coming away with a great image are better. You might think f/11 gets you just the right depth of field. But just for kicks, you go ahead and shoot at f/8 and f/5.6. Then you go the other way and shoot at f/16 and f/22. Later at the computer, you like the f/11 image but then when you look at the one at f/8 you see that, while there is a little softness at the edge of the flower, the background is much more pleasingly blurred than the one at f/11. Since you didn’t really look hard at the background while you were in the field, paying more attention to the subject (understandable), you didn’t notice the too-focused background.
So you end up going with the one at f/8, something you couldn’t do if you had not bracketed for aperture. When taking portraits of people outdoors you can take a similar tack. You can shoot at f/4 but also get one at f/2.8 and f/5.6. Then evaluate on your computer at home to see which is the best balance between clarity in the face and out-of-focus background.
The same thing can be done when shooting in shutter speed priority mode. If you’re panning or trying for motion blur, bracketing your shutter speed can save you. Say you think 1/30th sec. is the thing when you’re out there shooting. But later you find that 1/20th gave a better image. Of course you can check results on the LCD and experiment. But going with a plan to bracket gives some structure to your shooting and allows you to concentrate on capturing moving subjects, and also on technique (important when panning for e.g.).
MORE TO CONSIDER:
- You can think of bracketing as structured experimentation, and there is, in my opinion, a continuum between experimentation and bracketing. You will certainly want to experiment in the traditional way; that is, shoot, look at the LCD, adjust and shoot again. But it is quicker and more efficient in many cases to bracket.
- Think about how fine you want to get. You could, for example, bracket at +/- 1/3 stop increments all the way to +/- 2 stops. When you’re dealing with exposure, this might not be necessary; whole stop increments are likely good enough given your software’s ability to do the rest. When you’re dealing with panning or motion blur, however, 1/3 or 1/2 stop increments might be necessary.
- With exposure bracketing, your camera (if it’s a DSLR or micro 4/3) will usually allow you to take the bracketed shots automatically. This is normally set through the exposure compensation menu choice. If you are hand-holding the camera set it on burst mode so that all three (or sometimes five) shots are taken in succession. If you’re on a tripod, skip burst mode and just take them one after the other.
- You can bracket your ISO. If you are shooting stars at night (and don’t want star trails), your shutter speed is limited to 20 seconds or so. Your aperture is also usually fixed (nearly always wide open). There is only one variable left to change, and that’s ISO. Later you can check the images on your computer monitor at home for that perfect balance between density/brightness of the star field and noise. This is difficult to do in the field, as much because of your bleary eyes late at night as your camera’s imperfect LCD.
- You can also bracket your white balance. This is only really necessary if you shoot Jpegs. If you shoot RAW you can change your white balance in post-processing while not worrying about introducing artifacts like noise. Many DSLRs will even allow you to set the white balance bracket so your camera will shoot it automatically, as it does with exposure bracketing.
- Bracketing for exposure is necessary when shooting for HDR. If you’re planning on doing HDR, you’ll need to bracket those high-contrast scenes you feel might be good candidates. Many photographers will shoot 5, 7 or even 9 pictures, each separated by 1 or 2 stops. They might not use all of them in their final image; often 3 is all you need. With HDR, you need to use a tripod and make sure each picture is the exact same frame as the last. Otherwise your software might have trouble lining things up.
- Since bracketing is yet another thing to think about before shooting, introduce it slowly. Don’t let it get in the way of thinking about light and composition. These should always come first. Try first bracketing for exposure. The experimentation method mentioned above is a slower, more measured way to handle the rest of your shooting. Bracketing aperture (depth of field), shutter speed (motion blur) and other variables should be a natural extension to experimentation. It will eventually speed up your shooting, but there really is no reason to rush it.
Bracketing is by no means a relic of the film days. It can be a way to expand the options you have during post-processing, allow you to improve selected images or render them using more advanced software. It can lend structure and efficiency to your shooting. Most importantly, it can result in more keepers, improving your portfolio in the process. Have fun out there and thanks for looking!
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