Missing Pages: Bracketing
The Missing Pages column is a collection of all of the information that should have been included in your camera’s Owner’s Manual—but somehow got left out. This is a hybrid assortment of short articles that delivers the know-how you need to derive the maximum enjoyment—and creative expression—from your equipment.
It’s sort of a juiced-up User Guide for creative people who are not necessarily technical. Each part will teach you how to use one of the camera features or functions that you previously ignored or left set on Auto. And each will include a Creative Project so that you can try some scripted experimentation.
We will explain complex technical subject matter a way that everyone can understand. And if you happen to be a technical expert yourself, we’re including “Nerds Only” sidebars just for you. That way you can dig in deep—or just straddle the edges—of the technological stuff. It’s your decision.
Installment VI: Bracketing
Definition: a technique that produces a short sequence of images of which one is always captured at the camera settings thought to be correct, and the others at fixed intervals above and below that setting.
Bracketing is one of the single-most important techniques a creative photographer has in his or her arsenal. And it’s easy to do and easy to understand if you think of it like this: not enough, just right, too much.
Back in the day when cameras were not as automatic and often didn’t even have built-in exposure meters, photographers regularly guessed exposure settings. Some became very good at it, too. I can still recognize when the light level requires a setting of 1/30 of a second at f/2.8 using Tri-X (ASA 400) film. To make certain that important shots were properly exposed, it became routine to bracket exposures: right on, one-stop over and one-stop under. To be sure, today’s modern cameras deliver more reliable results than this system did, but an argument can be made that this discipline required photographers to be more intimately involved in exposure and helped them develop a keener understanding of light.
Exposure bracketing may no longer be a necessity, but there are times when it’s irreplaceable—harshly backlit scenes, for instance, can fool even the best built-in light meters. When shooting a subject against the open sky, bracketing can give you a dramatic silhouette in addition to a correctly exposed image.
Many people confuse Autobracketing with the act of Bracketing itself. You’ll find some Owner’s Manuals that list Autobracketing but not Bracketing. We can thank digital cameras for that—many digital cameras can produce a series of bracketed images from a single button press, once the settings have been correctly dialed in.
Depending on your camera brand, Autobracketing can be applied to Exposure, Flash Exposure, White Balance, Focus and other parameters. Of course, you can manually bracket just about any setting that’s adjustable. Even simpler cameras that lack Manual Exposure can be made to bracket by setting the Exposure Compensation dial to plus, then zero, then minus.
In the case of Exposure Bracketing, the results are usually three images: one that is captured underexposed, one at the normal setting and the last overexposed. Sometimes five or even seven separate, incrementally different images are recorded. The deviation is usually 1/3 stop or 1/2 stop or even 1-full stop, depending on the lighting conditions. Sometimes the order is reversed, and occasionally the “normal” exposure is captured first, before the variations. Don’t worry—you’ll be able to see the difference.
But which exposure variable was changed? That’s the real question, and the answer is dependent on the brand of your camera. It is critically important for you to understand how your camera handles exposure bracketing. Some cameras randomly change the f/stop or shutter speed and you lose control over those critical settings.
The Nikon D5000, for example, adjusts the exposure depending on the exposure mode you select. If you bracket while shooting in Aperture Priority, it changes the shutter speed. Likewise, in Shutter Priority it varies the aperture setting. In Program mode it slides up and down the program slope and changes either or both. And if you have ISO sensitivity set to Auto, the D5000 will automatically adjust that too “for optimum exposure when the limits of the camera exposure system are exceeded” (page 103 of the Nikon D5000 User’s Manual).
The second most popular parameter to bracket is White Balance. If you’ve ever been disappointed by an otherwise perfect shot that’s too green (under fluorescent light) or too blue (outdoors) you can easily understand why. It’s true that in many cases you can correct the color in Photoshop, but it’s valuable to have a good clean white to start with and bracketing the White Balance setting is one way to secure that. The better solution, of course, is to shoot RAW and make your white balance adjustments when you decode the file. But not every camera records in RAW file format and not every photographer uses RAW every time. That explains why even high-end RAW capture machines like the Canon EOS 5D Mark II allow you to Autobracket White Balance.
In reality, the camera is simply adding a finite amount of color bias in one of four directions: amber, blue, green or magenta. Some cameras offer only amber/blue options. Varying amber and blue allow you to improve images captured under regular old tungsten house lights as well as daylight. The green and magenta settings are primarily for certain types of fluorescent tubes. With most cameras that offer Autobracketing of White Balance, you can set the amount of color bias that’s applied. When set on White Balance Autobracket, the Nikon D5000 captures one image and processes it three ways to alter the color. You can add one, two or three units of blue and amber plus the normal color rendition.
White Balance Autobracketing—alone or in conjunction with manually applied variations—is a powerful tool and a great, creative way to explore a scene. And your camera may have another unique feature that can be bracketed. For example, the Nikon D90 and D5000 cameras allow you to bracket Active D-Lighting effect. Active D-Lighting is a feature that essentially extends dynamic range by preserving details in highlight areas and in shadows. Dig out that Owner’s Manual and check it out.
One word of caution: make sure the subject doesn’t move between shots when you’re doing any sort of bracketing. That seems like common sense, but you’d be surprised how many people try to bracket a street scene, flower that’s blowing in the wind or rapidly changing sunset and wonder why the sequence appears abnormal. If your camera can capture three or four frames per second, the results should be fine—just make sure you have the drive mode set accordingly. If you are slowly or manually bracketing, be wary of changes in the scene.
Bracketing exposure—either automatically or manually—is too easy to be a Creative Project, but you should run through the steps enough times that you’re comfortable shifting into bracket mode when necessary. And you might be surprised by the difference a 1/3 or 1/2 stop makes, particularly in scenes that are High Key (tones ranging from middle gray to white) and Low Key (tones ranging from middle gray to black). Most important, study the metadata of bracketed images to learn how your camera adjusted itself. As mentioned above, the ideal way is to keep either the f/stop or shutter speed constant while varying the other.
If your camera offers automatic White Balance bracketing, select a scene or subject that contains something that’s pure white. Purists will want to experiment with scenes that have two or all three of the primary colors as well. I find that commercial signs, the sort that hang above business storefronts, often fill the bill perfectly. If you live near an area that has a carnival-type atmosphere—a boardwalk on the Jersey shore, for example, or something akin to the equally flush (although temporary) Taste of Milwaukee celebration—you’ll have no trouble finding white signs with colorful lettering. The assignment is to explore the White Balance Autobracket feature at different times of day: (ideally) dawn, midday and dusk. Short of that, midday and either dawn or dusk.
For Nerds Only
On May 23, 2001, Minolta Corporation officially introduced the world’s first 5-megapixel digital camera, the Minolta DiMAGE 7. This model had been exhibited—under glass—at the Photo Marketing Association trade show the previous February, and in fact won a prestigious DIMA Award from that organization. One of the unique features of this marvel was Autobracketing of four different parameters.
The DiMAGE 7, fondly remembered by many because of its insatiable appetite for double-A batteries, featured Autobracketing of Auto Exposure, Subject Contrast, Color Saturation and Filter Effect. The Filter Effect option was especially cool. In the right hands, the DiMAGE 7 was a powerful tool that offered high resolution, outstanding image quality, a sharp 7X manual zoom, 28mm wide angle coverage and other leading features. In many ways it was ahead of its time. It also had another unique feature—one that may incite you to buy one secondhand.
The DiMAGE 7 lacks an IR-cutoff filter. That means IR (Infrared Light) passes freely to the CCD. Used with a deep red IR filter, you can capture some extraordinary IR images. To the right is an image captured with a DiMAGE 7 by noted photographer and infrared expert Steve Rosenbaum. We’ll learn more about IR in future segments of Missing Pages.
Text ©2009 Jon Sienkiewicz.
Text ©2009 Jon Sienkiewicz.