Our cameras are wonderful tools. They can measure the available light and use that information to make a good guess about what settings are required to get the highlights, shadows and everything in between pretty close to the way it was in real life. As photographers, we rely on our cameras and metering system to do this job - without those metering systems, we'd have to use our eyes and brains to figure out the right shutter speed and aperture combination.
But here's the thing: all that wonderful technology still isn't good enough to guarantee perfect results every single time. Your camera does a pretty good job of most of the time But it can't account for all those different variations in light that might happen in unusual situations.
That's where bracketing can work well. Today, we'll look at bracketing, why it works, and how you can bracket your own images without needing to let the camera do it.
[ Top image Eric's Composite Setup by Flickr user Andrew Vicars]
As an extreme example of when your camera chooses an incorrect exposure: let's say you're photographing a snowy landscape. Snowy landscapes are mostly white, not middle gray, so your metering system will likely underexpose them. Likewise, when you shoot a very dark seen such as, say, a black cat sitting in the mouth of a cave, your meter may decide to overexpose the scene because it assumes that all those blacks are middle grays.
853 Black Cat 1 by Flickr user Nebojsa Mladjenovic
There are much less extreme examples than these, of course—you're probably a lot more likely to encounter situations where there is some slight underexposure or slight over exposure, based on the fact that all the tones in the scene average out to be just a little bit darker or a little bit lighter than middle gray. So lets say you find yourself in a situation where the light is just weird and your camera keeps getting it wrong? One thing you can do is use your spot metering system, which will let you take a meter reading from a very small point in the scene—ideally one that is roughly middle gray. But you may find it simpler to just bracket your shots.
What is bracketing?
Bracketing is a very simple way to give yourself the best odds of getting a perfectly-exposed photo in a tricky lighting situation. The concept is really simple—you just take a series of photos at three different exposures, one below where your meter reading is, one at the reading itself, and one over the meter reading. With JPG files you generally don't need to bracket in increments of greater than 1/2 or 1/3rd, because JPGs don't capture a very broad range of tones to begin with, so the margin of error is smaller. If you're shooting in raw, you can bracket one stop between exposures to give yourself more flexibility in post processing, if you need it.
Many cameras give you the ability to take bracketed shots without having to look at your camera settings at all. But some cameras don't. What if your camera is one of these? If that's the case, then you will have to familiarize yourself with some of the other ways to bracket.
Bracketing with exposure compensation
There are actually a couple of ways that you can handle this. The first is that you can shoot with exposure compensation. In most DSLRs, this is a setting that you can access using the buttons or dials on your camera, though in some point-and-shoot cameras you may need to go into the menu to find it.
Your exposure compensation function works like this: your meter takes a reading off of the scene and lets you know what it thinks your settings should be. If it seems to be getting it wrong or you're just not sure based on what you can see on the LCD, you add negative or positive exposure compensation in the hopes of getting a better exposure. Add positive exposure compensation to brighten the shot, add negative exposure compensation to darken it.
Exposure compensation generally gives you the ability to add or subtract exposure compensation in increments of 1/3rd to 1/2 stops. To use exposure compensation to bracket your shots, start by taking a photo with a negative exposure compensation of one half to one third. Then take a shot at zero exposure compensation. Finally take one at 1/3 to 1/2 overexposed. If you already know that your camera is overexposing or underexposing the image, you can do all your bracketing with negative or positive exposure compensation, respectively. For example, 1/2 stop, a full stop and 1 1/2 stops.
Bracketing in manual mode
Another simpler way to bracket without a bracketing function is to switch over to manual mode. If manual mode isn't something you're used to, this idea can be a little intimidating, but the good news is that it's really quite easy to bracket simple shots in manual mode. If you have a DSLR, all the information you need is located right in your viewfinder—you don't even need to look away to adjust your settings.
If manual mode isn't your thing, let me give you a quick primer. The first thing you need to do after putting your dial in the dreaded "m" position is look for the exposure level indicator inside your viewfinder. This typically looks like a dotted or dashed line with a plus on one end and a minus on the other. Depending on your camera model and manufacturer, there's usually a short vertical line or a zero right in the middle of that line. There may also be a series of ascending and descending whole numbers, starting with one. Do you see it? Good.
When your camera's meter thinks you've got the right aperture and shutter speed combination, it will tell you using the exposure level indicator. Again, the way it communicates this information is different depending on your camera—there could be a little hash mark below that zero or center point, or there could be a dotted line that gets longer as the image becomes more underexposed or overexposed. To find out, try adjusting your shutter or aperture and watch what happens to the exposure level indicator.
Now is where the bracketing part comes in. If your exposure level indicator has increasing/decreasing whole numbers on either side of the middle point, those numbers represent a stop of over or underexposure. So when the marker is under the 1 on the minus side, that's one stop underexposed. If it's under the two on the minus side, that's two stops underexposed, and so on. But there are also points in between—either half stops or third stops (again this depends on your camera).
Canon 1000D Back by Flickr user Amy Dianna
Once you've got this figured out, try framing a scene. Watch the exposure level indicator. If that marker is somewhere between the middle point and the plus, your camera's metering system thinks your settings will overexposed the shot. If it's somewhere between the middle point and the minus, your camera's metering system thinks there's going to be some underexposure. So now, you get to choose—you can increase/decrease your shutter speed until the marker lands in the middle, or you can increase/decrease your aperture to achieve the same results.
So start with the reading your meter thinks is the right one, then choose an aperture/shutter combination that puts you 1/2, 1/3 or a whole stop into the minus side (depending on your camera and file format). Shoot one exposure at those settings, then take one at the middle point, then take a third that is 1/2, 1/3 or a whole stop into the plus side. Those are your bracketed shots. Again, you can also do all your bracketing on the positive or negative side if you need to.
Now remember when you're doing this that it does matter whether you increase/decrease your shutter speed or whether you increase/decrease your aperture. Think it through before deciding where you're going to make the changes. If you're shooting for depth of field, you may want to change your shutter speed so that you can maintain the same depth of field across each bracketed shot. If you're shooting in low light, you may want to adjust the aperture instead, so your shutter speed won't fall below the point where you'll start to see motion blur.
This is almost as easy as auto bracketing. To be sure, auto bracketing is nice because you don't have to put a lot of thought into it, but doing it in manual mode gives you more control. It also makes you a lot more aware of how the bracketing is affecting your images. And once you know that, you can stop bracketing altogether and then continue to shoot using the settings that are working for you for as long as you remain in those lighting conditions. Easy! No auto bracketing required.
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