In this article I’ll cover everything there is to know about what Exposure Bracketing is, why and when you’ll need it, and how to successfully take a exposure bracketed shot. An essential procedure in creating a high dynamic range (HDR) shot.
Have you ever looked at your photographs and thought that bright white washed out sky just isn’t the lovely blue sky filled with clouds you remember? Or that dark foreground just isn’t the bright lush green you saw in real life?
Exposure bracketing is when your camera takes multiple shots of the same scene, but with different shutter speeds that result in different exposures. A minimum of two shots is required, but most common would be three to better capture the dynamic range. For the example below, I’m using three different exposures; a correctly exposed photo, an under exposed photo and an overexposed photo.
The following photographs (from left to right) are taken with 0EV, -3EV and +3EV.
The normally exposed photograph (0 EV @ 1/200 sec) is what the camera works out to be the best overall exposure for the scene (based on your cameras settings). The under exposed photograph (-3EV @ 1/1600 sec) is taken with a faster shutter speed, resulting in a darker photograph due to the lesser amount of light hitting the cameras sensor. The over exposed photograph (+3EV @ 1/25 sec) is taken with a slower shutter speed, resulting in a lighter photograph due to the excessive amount of light hitting the cameras sensor.
Why and When
Have you ever looked at your photographs and thought that bright white washed out sky just isn’t the lovely blue sky filled with clouds you remember? Or that dark foreground just isn’t the bright lush green you saw in real life? The reason is, your cameras sensor simply can not see what your eyes can, and under non-perfect conditions your picture simply will not represent what you actually saw. So when you’re trying to capture a scene with a high amount of contrast or tonal range, you’ll need a range of different exposed shots in order to cover the whole range of lighting conditions.
As you can see above, the three different photographs result in very different looking images. You might ask yourself why would one want to take all these different images, most of which look unusable? Well, each photograph has a section of the image that you’re going to need. The under exposed image (-3 EV) has a perfectly exposed sky, the normally exposed shot (0 EV) has great exposure for the midtones, and the over exposed shot (+3 EV) has captured all the details in the shadows. Once you combine these, you’ll have a perfectly exposed high dynamic range photograph, like below.
The most important of them all. Getting it right when it comes to the crunch! A badly taken bracketed shot will result in them unable to be used for blending together.
Identify whether your scene requires multiple exposures.
This might seem pretty obvious, but you’d be surprised how many times this first step is missed. Often a single exposure combined with a slight adjustment of a few sliders in Lightroom will be suffice. However, many times the light your shooting is just to varied for your camera to capture in one shot. Does your scene have bright sections (like a bright sky or is the sun in your photo?). Does your scene also have a large amount of dark sections (a foreground in shadow from trees, rocks, buildings?). If so, this is potentially a scene that needs multiple exposures. Shooting into the sun is a great example of high tonal range scenes. Indoor shots with windows are another classic example.
A good way to determine if you need to bracket is to look at your cameras histogram. This will show any clipped areas to the right (too much light) or the the left (too dark).
Get out your tripod.
Once you’ve identified that your scene is one that needs multiple exposures, it’s time to set up and start shooting. For this I definitely recommend a tripod to keep your framing the same on each shot. It is true that you can potentially pull it off with a steady hand, good lighting for a fast shutter speed (and a camera with a fast burst rate). But if you want to be sure – use a tripod. So, in short, just mount your camera on a tripod!
Setup your Auto Exposure Bracketing.
Most cameras these days have an Auto Exposure Bracketing (AEB) setting in the camera which you can customise from shooting anywhere from 3 to 7 photographs. I’d say it’s rare that you’ll need 7, but of course the more you do, the more options you’ll have to use. I mostly just use 3, and sometimes 5 depending on how “contrasty” the scene is. You also need to set the exposure compensation amount. This basically is the exposure difference between each of the photographs. The larger stop difference you choose, the greater exposure difference it will be. For the examples above, and the menu screen print below, I have used 3 bracketed shots at -3 EV (1/1600 of a second), 0 EV (1/200 of a second) and +3 EV (1/25 of a second), resulting in a shutter speed difference from 1/25 of a second on the +3 EV shot, to 1/1600 of a second on the -3 EV shot. With 1/200 of a second in the middle. Using +-1EV will result in the same shutter speed for the correct exposed shot, but the other two will be much closer, resulting in a smaller variation in. Each scene will have to be judged different depending on its requirements.
The screen shot below is from a Canon SLR. Each manufacturer will have their own menu system (a quick flip of the manual will reveal where to go).
You can of course manually adjust the exposure compensation dial (or shutter speed) for each separate photos to achieve the same result, but with AEB software, there is no need.
Use a remote or 2 second timer.
Use a remote, or 2 second timer to fire the shutter release. By doing this, you’ll reduce the chance of camera shake that your finger may generate on the first shot, which is especially true on lower light bracketed shots that require longer shutter speeds.
Congratulations, you’re done! Your camera will fire off 3 or more shots automatically and you’ll have your array of multiple exposure shots ready and waiting.
Of course, this is just the beginning. You now need to import these into your favourite editing software and combine them to create a high dynamic range photograph.