Boulevard of Photographers provides here some techniques to use the bracketing features found in cameras.

Auto Bracketing is a function that is appearing increasingly as a part of many cameras' feature set, but while standard exposure bracketing has been around for a number of years, digital photography takes the concept further, and a range of bracketing functions are available. While bracketing for one thing or another is often possible manually, auto bracketing makes the process easy, and error-proof. With this article, we'll explain each type, and show its effect.

The concept behind bracketing is simple, it is a way to ensure that at least one image will be "perfect". This is done by capturing images with variations over one of the parameters that controls the quality of the exposure. With film cameras, the process automatically adjusts either the aperture or the shutter speed in modest increments, capturing 3 images of the same subject at a slightly different exposure settings. With digital cameras, the process can be additionally varied over other parameters.

If you are a beginner, Boulevard of Photographers advises you to use the auto-bracketing feature.

Exposure Auto Bracketing

Of all the auto bracketing systems, automatic exposure bracketing is the oldest and the most commonly available. Most commonly, exposure bracketing can be thought of as a way to vary the brightness of the exposure over a series of 3 frames. Some systems however take it further and offer bracketing over a series of 5 frames if desired. The increment used for the bracketing is determined in fractions of 1EV (exposure value) steps.

  The auto bracketing process is fast, and usually records the first exposure using the values decided by the camera's meter, then one under exposure captured at the predetermined, or default, setting, then another exposure, this time slightly over exposed by the same increment. With some cameras the order in which each exposure of the bracketing process is done can be selected. For example, using zero to represent the camera's standard exposure, the process can be 0, -, +; or -, 0, +; or +, 0, -; which allows a lot of flexibility.

If exposure bracketing is within the capabilities of both film, and digital cameras, other types of bracketing are not. With some digital cameras, bracketing is possible for Contrast , Saturation , Colour , White Balance , and even Focus.

Contrast Bracketing:

In the domain of film, any contrast control is done in the lab, during the development, or printing stages. But with a digital camera, contrast can be manipulated electronically, directly in the camera much the same as can be done with image editing software, post capture. We at Boulevard of Photographers generally think that efficient use of contrast bracketing can create interesting photography compositions.

Contrast bracketing uses a similar system to exposure bracketing, but the increments are usually shown as plus or minus . Some cameras provide for a gradual increase of the contrast over a number of steps as much as 5 steps. while others simply provide for increased and decreased contrast.

Depending on the subject, the contrast variations can be difficult to detect, especially with colour photos, so in the example below a black and white image is used:

Normal Contrast	Increased Contrast	Decreased Contrast

With colour photos, the change in contrast can usually be seen with the depth of the shadows, or in the range between dark and light objects, or with green foliage, as can be seen in the example below:

Normal Contrast	Increased Contrast	Decreased Contrast

Saturation Bracketing

Saturation bracketing is another type of auto bracketing that is available with some cameras. With it, the camera will automatically increase or decrease the colour saturation of the image. While often the effect is subtle, it can be quite noticeable, particularly when there is a lot of blue sky in the photo.

Normal Saturation	Increased Saturation	Decreased Saturation

White Balance Bracketing

Auto bracketing of the white balance is once again a type of feature that can only be had with a digital camera. Unlike saturation bracketing, which uniformly affects the strength of all colours, cameras that offer the white balance bracketing feature will generally capture one image as their auto white balance determines it should be, followed by one image with heightened blue tones, and one with heightened red tones, as depicted in the example below:

Normal White Balance	Increased Blue Tones	Increased Red Tones

Sharpness Bracketing

Auto Sharpness Bracketing is becoming more common. As photos are captured, the internal image processing of the camera often performs sharpening. Indeed, many cameras currently offer an option to increase or decrease the sharpening applied to the photo when the camera processes the image prior to saving it.

With auto bracketing for sharpness, three images are saved: one with the default sharpness of the camera, the next with a softer sharpness, the third with increased sharpness. To show the variations, we've selected a small part of the entire subject shown at left, and that section is shown below at the different levels of sharpness recorded by the camera.

Normal	Softer	Sharper

This type of control over sharpness is very useful with portrait photography. A sharp image tends to emphasize small details that would not be normally visible, so a softer focus tends to create a more natural looking image.


Focus Bracketing:

Focus bracketing is a new development, and at this time not wide spread. Currently the system is employed on digital images that are manually focused using an LCD monitor.

The examples below illustrate the system:

Selected focus point (centre)	2nd frame focused behind	2nd frame focused in front

Focus bracketing works by capturing the first image as it has been focused by the user, then one in which the focus point is a little bit behind the point selected by the user, followed by another image in which the focus point is a bit in front of the user's focus point.

The resolution of monitors is relatively low , however nice an image they have , and manually focusing a subject based on the image they show is often difficult.

Many cameras provide a magnification of the central part of the image to assist manual focus, but even that is not very precise. Focus bracketing is an attempt to overcome that lack of precision.

So, Boulevard of Photographers encourages you to shoot photographs with diverse bracketing mode in order to experiment.