Photography News Issue 48

Photography News | Issue 48 | photographynews.co.uk Technique 47 Camera School PART 13 Here we lift the lid on all things camera related, showing how to get better results from your CSC or DSLR, and providing all the info you don’t find in the manual. So, stick with us and you’ll soon be wielding your camera like a pro. This month, how to set up exposure bracketing and use it to improve your pictures

Words & pictures by Kingsley Singleton

Over the last few months we’ve talked about the different exposure settings on your camera (aperture, shutter speed and ISO), and how they combine to create an image. According to the exposure mode you’re using, these can be set completely manually (manual), semi- automatically (shutter or aperture-priority), or fully automatically (auto or program). In all but manual mode, the camera uses its metering system to take a reading of the scene, then sets what it thinks will make a good exposure. What is bracketing? Exposure bracketing is a mode that creates darker and/or lighter images as well as the base exposure that the camera has metered. How much darker or lighter depends on the settings you use, andwhat the camera is capable of. You can also vary the number of shots taken. Bracketed images are shot in sequence, and how the exposure is darkened or lightened depends on the mode you’re shooting in: if you’re shooting in aperture-priority mode, the aperture will remain constant with the shutter speed increasing and decreasing to make the image lighter or darker; if you’re in shutter- priority it’s the aperture that will open or close to make the change in exposure; if you’re in program, bothmay change. Like other exposure settings, the variation in exposure is defined in stops; either full stops

like 1EV, or fractions of them such as 0.3EV or 0.7EV. So a three-shot bracket, at a variation of 1EV, taken in aperture-priority mode, would cover shutter speeds of, for example, 1/60sec (the base exposure), 1/30sec (the brighter exposure) and 1/125sec (the darker exposure); change the exposure to variation to 3.0EV and you’d get 1/60sec, 1/8sec and 1/500sec. Why is bracketing useful? Bracketing is helpful in situations when you’re not sure of the exposure you need, such as when the subject is backlit or when parts of the scene are much brighter or darker than others. After shooting a bracketed sequence you can pick the exposure that looks best, or you can use all you’ve shot to make the final image in editing; a method called exposure blending or high dynamic range (HDR) processing. If you’re doing the latter, you’ll need to ensure there’s no change in camera position between the shots, so using a tripod is essential

-1EV

0EV

+1EV

How to use exposure bracketing Although you can bracket manually, using either manual mode or the camera’s exposure compensation setting to produce lighter and darker exposures, the easiest way is to use the auto exposure bracketing (AEB) function. In this mode, accessed via a button on the body or via the shooting menu, you choose the number of frames and method of bracketing, then the amount of exposure change between shots. You can usually choose to create shots lighter and darker than the base exposure, or just shots that are lighter, or shots that aredarker. Most of the time, it’s best to shoot bracketed exposures in aperture-priority, so that the depth-of-field in the image doesn’t change. For the same reason, you should keep the focus in the same place for each shot. For the simple three-shot bracket used to

make the example here, I shot in aperture- priority mode on a Nikon D810. I pressed the bracketingbutton(BKT),dialledin‘3F’denoting three frames, then set the exposure increment to 1.0EV. With the camera on a tripod and in self timer mode, this produced exposures of 1/2sec, 1sec, and 1/4sec at f/16. If there had been more variation of light in the scene, like a brighter sky or a more shadowed foreground, I could have set the exposure increment to 2.0EV or 3.0EV, or set the number of frames to five, seven or nine for greater coverage.

What to dowith bracketed shots

After you’ve shot your bracketed images, you can either pick the exposure that suits what you wanted, or use the separate exposures to make a final image via exposure blending or HDR processing. Exposure blending is the simplest of these options, and can be done in Photoshop using Layers plus the Eraser tool, or Layer Masks, as shown right. In the example image, I used Layer Masks to show the top of the darker exposure for the sky, and parts of the two lighter ones for the foreground. This method is essentially similar to using a graduated filter at the time of shooting, but affords more control of which areas are actually darkened; for instance the mountainside can be kept lighter than it would be if using a graduated filter alone.

NEXTMONTH Perfect panning without pain with our expert advice. Join us again next month for more top technique tips