Multiple camera shots with different expose combined in HDR photo
If you are just starting out in digital photography, you have probably never heard about auto exposure bracketing (AEB). If you are an enthusiast photographer, probably you have heard about this but never quite mastered the concept to use it with confidence. Regardless of your expertise in digital photography this article can help you master an extremely important feature of your DSLR, i.e.; auto exposure bracketing (AEB).
Why should I use AEB?
The main reason you would want to use AEB is to bracket your shots for the optimum exposure. Bracketing denotes taking several images of the same scene but at different exposure values. Often, when shooting a landscape scene, you are faced with the problem of pockets of intermittent highlight and shadow areas in the frame. It may be possible that the foreground is dark whereas the sky and the rest of the background is bright. If you attempt to expose for the foreground you risk losing the sky. On the other hand if you expose for the sky your foreground could be clipped in shadows. Then there could be deep shadows cast by the trees around the bottom of the frame. These are quite tricky to manage.
Unless you have mastered the zone system devised by Ansel Adams and Fred Archer, the best option in this situation would be to take two exposures of the scene. One of the exposures would have the sky properly exposed and the other one would have the foreground. Later on you can combine the two images in any photo editing software to create one properly exposed image.
A word on HDR photography
This technique of combining two or more images in a photo editing software to create a single properly exposed image is also known as High Dynamic Range photography or HDR photography. I can imagine some of you sitting up reading about HDR. This is a technique that is being increasingly used. However, just like any other technique in photography, it is not advisable to overdo this technique. There have been some really sloppy attempts at creating HDR images of scenes which are perfectly ok to begin with.
Two is the minimum number of images that you need to make in order to create an HDR image. Some scenes can require up to 4 or more exposures to capture all the dynamic range. This of course depends on how much dynamic range is there in the scene and how much of it can be captured by your camera in a single frame. This is where cameras like the Nikon D800 and D800 E really make their presence felt with their high dynamic range.
If you want to dabble into HDR photography but find the post-processing thing a bit too intimidating, try outsourcing the task to one of the Photoshop post-processing professionals on Phowd. This way you can concentrate on taking images and have your images processed by professionals.
Why can’t I do this manually?
If you had to take the images manually, each time adjusting the exposure for different areas of the frame, you would have definitely knocked the camera about. Resultantly, the frame would have been altered. Even the tiniest bit of movement would ruin an HDR attempt and there is no way to correct that in post-processing without cropping the image. This is why the AEB tool is so important. Using AEB the camera itself adjusts the exposure value thereby not requiring you to tinker with the settings in between the exposures. Thereby you eliminate the need to touch your camera in between exposures. All you need to do is set the number of exposures you need, the amount of exposure compensation to use between each exposure and press the shutter release.
How to use AEB?
The steps to use AEB is different for different cameras makes and models. So, it is highly recommended that you check the manual that came along with your specific camera model. The steps mentioned here are specific to the Nikon D7000 but should work with all DSLR cameras.
The first step is to press the button that reads ‘BKT’, short for bracketing. When you press this you will notice the words ‘OF’ and ‘0.3’ appear on the top LCD (Nikon specific). If your DSLR does not come with a top LCD, press the ‘Info’ button on your camera to turn on the display on the rear LCD monitor. You could alternatively look through the viewfinder while turning the rear command dial (also known as the main command dial of the D7000). You will notice the letters BKT appear on the viewfinder, meaning you are now in auto exposure bracketing mode.
Ok, coming back to ‘OF’. Here ‘OF’ means that exposure bracketing is off and ‘0.3’ refers to the default setting of 1/3-stop exposure compensation. You can change the amount of exposure compensation to use in increments of 1/3-stop all the way up to 2-stops. Turning the main command dial left or right gives you option to select the number of frames to shoot. Turning the sub-command dial left or right increases or decreases the extent of exposure compensation used.
Finally, you may want to use a tripod as that ensures your camera is not wobbling or moving about between the shots. Choose something that is sturdy and is not easily knocked about. Carbon-fiber tripods are best.
One more adjustment that you need to do is set your camera on continuous shooting mode. This way you need to press the shutter release only once and the camera will make the exposures one after the other while adjusting for the exposure compensation between each shots. In order to switch to continuous shooting mode on D7000, rotate release mode dial to CL (Continuous low speed) or CH (Continuous high speed).