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photography Photography is the art, application, and practice of creating durable images by recording light, either electronically by means of an image sensor, or chemically by means of a light-sensitive material such as photographic film. It is employed ...
, bracketing is the general technique of taking several shots of the same subject using different camera settings. Bracketing is useful and often recommended in situations that make it difficult to obtain a satisfactory image with a single shot, especially when a small variation in exposure parameters has a comparatively large effect on the resulting image. Given the time it takes to accomplish multiple shots, it is typically, but not always, used for static subjects.
Autobracketing Autobracketing is a feature of some more advanced cameras, whether film or digital cameras, particularly single-lens reflex cameras, where the camera will take several successive shots (often three) with slightly different settings. The images m ...
is a feature of many modern cameras. When set, it will automatically take several bracketed shots, rather than the photographer altering the settings by hand between each shot.


Types of bracketing


Exposure bracketing

Image:StLouisArchMultExpEV-4.72.JPG, –4 stops Image:StLouisArchMultExpEV-1.82.JPG, –2 stops Image:StLouisArchMultExpEV+1.51.JPG, +2 stops Image:StLouisArchMultExpEV+4.09.JPG, +4 stops Without further qualifications, the term ''bracketing'' usually refers to exposure bracketing: the photographer chooses to take one picture at a given exposure, one or more brighter, and one or more darker, in order to select the most satisfactory image. Technically, this can be accomplished by changing either the shutter speed or the aperture, or, with digital cameras, the ISO speed, or combinations thereof. Exposure can also be changed by altering the light level, for example using neutral-gray filters or changing the degree of illumination of the subject (e.g. artificial light, flash). Since the aim here is to alter the amount of exposure, but not otherwise the visual effect, exposure compensation for static subjects is typically performed by altering the shutter speed, for as long as this is feasible. Many professional and advanced amateur cameras, including
digital camera A digital camera is a camera that captures photographs in digital memory. Most cameras produced today are digital, largely replacing those that capture images on photographic film. Digital cameras are now widely incorporated into mobile device ...
s, can automatically shoot a bracketed series of pictures, while even the cheaper ones have a less convenient but still effective manual
exposure compensation Exposure compensation is a technique for adjusting the exposure indicated by a photographic exposure meter, in consideration of factors that may cause the indicated exposure to result in a less-than-optimal image. Factors considered may include ...
control. Exposure bracketing is indicated when dealing with high-contrast subjects and/or media with limited
dynamic range Dynamic range (abbreviated DR, DNR, or DYR) is the ratio between the largest and smallest values that a certain quantity can assume. It is often used in the context of signals, like sound and light. It is measured either as a ratio or as a base-1 ...
, such as transparency film or CCD sensors in many digital cameras. Exposure bracketing is also used to create fade-in or fade-out effects, for example in conjunction with multi-vision
slide show A slide show (slideshow) is a presentation of a series of still images (Presentation slide, slides) on a projection screen or electronic display device, typically in a prearranged sequence. The changes may be automatic and at regular intervals o ...
s, or in combination with
multiple exposure In photography and cinematography, a multiple exposure is the superimposition of two or more exposures to create a single image, and double exposure has a corresponding meaning in respect of two images. The exposure values may or may not be ide ...
or flash. When shooting using
negative film In photography, a negative is an image, usually on a strip or sheet of transparent plastic film, in which the lightest areas of the photographed subject appear darkest and the darkest areas appear lightest. This reversed order occurs because t ...
, the person printing the pictures to paper must not compensate for the deliberately underexposed and overexposed pictures. If a set of photos are bracketed but are then printed using automated equipment, the equipment may assume that the camera or photographer made an error and automatically "correct" the shots it determines are "improperly" done. Images produced using exposure bracketing are often combined in postprocessing to create a high dynamic range image that exposes different portions of the image by different amounts.


Flash bracketing

Flash bracketing is a technique of working with electronic
flash Flash, flashes, or FLASH may refer to: Arts, entertainment, and media Fictional aliases * Flash (DC Comics character), several DC Comics superheroes with super speed: ** Flash (Barry Allen) ** Flash (Jay Garrick) ** Wally West, the first Kid ...
, especially when used as fill flash in combination with existing light, maintaining the overall amount of exposure. The amount of light provided by the flash is varied in a bracketed series in order to find the most pleasing combination of ambient light and fill flash. If used for this purpose, flash bracketing can be differentiated from normal exposure bracketing via flash, although the usage of the term is not strict. Alternatively, if the amount of flash light cannot be altered easily (for example with studio flashes), it is also possible to alter the aperture instead, however, this will also affect the
depth of field The depth of field (DOF) is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image captured with a camera. Factors affecting depth of field For cameras that can only focus on one object dist ...
and ambient light exposure. If the flash to ambient light ratio is to be changed in flash bracketing using this technique, it is necessary to counter-shift the shutter speed as well in order to maintain the level of ambient light exposure, however, with
focal plane shutter In camera design, a focal-plane shutter (FPS) is a type of photographic shutter that is positioned immediately in front of the focal plane of the camera, that is, right in front of the photographic film or image sensor. Two-curtain shutter ...
s, this is often difficult to achieve given their limited
X-sync In photography, flash synchronization or flash sync is the synchronizing the firing of a photographic flash with the opening of the shutter admitting light to photographic film or electronic image sensor. In cameras with mechanical (clockwor ...
speed - and flash techniques such as
high-speed synchronization In photography, flash synchronization or flash sync is the synchronizing the firing of a photographic flash with the opening of the shutter admitting light to photographic film or electronic image sensor. In cameras with mechanical (clockw ...
are not available with studio flashes.


Depth-of-field bracketing

DOF (
Depth-of-field The depth of field (DOF) is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image captured with a camera. Factors affecting depth of field For cameras that can only focus on one object dist ...
) bracketing comprises taking a series of pictures in stepped apertures (
f-stop In optics, the f-number of an optical system such as a camera lens is the ratio of the system's focal length to the diameter of the entrance pupil ("clear aperture").Smith, Warren ''Modern Optical Engineering'', 4th Ed., 2007 McGraw-Hill ...
s), while maintaining the exposure, either by counter-shifting the
shutter speed In photography, shutter speed or exposure time is the length of time that the film or digital sensor inside the camera is exposed to light (that is, when the camera's shutter (photography), shutter is open) when taking a photograph. The am ...
or, with digital cameras, adapting the
ISO speed Film speed is the measure of a photographic film's sensitivity to light, determined by sensitometry and measured on various numerical scales, the most recent being the ISO system. A closely related ISO system is used to describe the relations ...
accordingly. In the first case, it will also change the amount of motion blur in the picture. In the second case, it may visibly affect image noise and contrast. Combining DOF bracketing with
multiple exposure In photography and cinematography, a multiple exposure is the superimposition of two or more exposures to create a single image, and double exposure has a corresponding meaning in respect of two images. The exposure values may or may not be ide ...
, the so-called ''STF effect'' (for ''Smooth Trans Focus'') can be achieved as implemented in the
Minolta Maxxum 7 The Minolta A-mount camera system was a line of photographic equipment from Minolta introduced in 1985 with the world's first integrated autofocus system in the camera body with interchangeable lenses. The system used a lens mount called A-moun ...
's automated
STF function Autobracketing is a feature of some more advanced cameras, whether film or digital cameras, particularly single-lens reflex cameras, where the camera will take several successive shots (often three) with slightly different settings. The images may ...
. This closely resembles the
Bokeh In photography, bokeh ( or ; ) is the aesthetic quality of the blur produced in out-of-focus parts of an image. Bokeh has also been defined as "the way the lens renders out-of-focus points of light". Differences in lens aberrations and ...
-pleasing optical effect of the
apodization In signal processing, apodization (from Greek "removing the foot") is the modification of the shape of a mathematical function. The function may represent an electrical signal, an optical transmission or a mechanical structure. In optics, it is p ...
filter in the Minolta/Sony STF 135 mm f/2.8 4.5s special-purpose lens.


Focus bracketing

Focus bracketing is useful in situations with limited
depth of field The depth of field (DOF) is the distance between the nearest and the furthest objects that are in acceptably sharp focus in an image captured with a camera. Factors affecting depth of field For cameras that can only focus on one object dist ...
, such as macro photography, where one may want to make a series of exposures with different positions of the focal plane and then choose the one in which the largest portion of the subject is in focus, or combine the in-focus portions of multiple exposures digitally (
focus stacking Focus stacking (also known as focal plane merging and z-stacking or focus blending) is a digital image processing technique which combines multiple images taken at different focus distances to give a resulting image with a greater depth of fiel ...
). Usually this involves the use of software with
unsharp masking Unsharp masking (USM) is an image sharpening technique, first implemented in darkroom photography, but now commonly used in digital image processing software. Its name derives from the fact that the technique uses a blurred, or "unsharp", negat ...
, a filtering algorithm that removes out-of-focus portions of each exposure. The in-focus portions are then "stacked"; combined into a single image. Focus stacking is challenging, in that the subject (as in all brackets) must stay still and that as the focal point changes, the magnification (and position) of the images change. This must then be corrected in a suitable application by transforming the image.


White balance bracketing

White balance In photography and image processing, color balance is the global adjustment of the intensities of the colors (typically red, green, and blue primary colors). An important goal of this adjustment is to render specific colors – particularly neu ...
bracketing, which is specific to
digital photography Digital photography uses cameras containing arrays of electronic photodetectors interfaced to an analog-to-digital converter (ADC) to produce images focused by a lens, as opposed to an exposure on photographic film. The digitized image is sto ...
, provides a way of dealing with mixed lighting by shooting several images with different white point settings, often ranging from bluish images to reddish images. When shooting in a camera's
raw Raw is an adjective usually describing: * Raw materials, basic materials from which products are manufactured or made * Raw food, uncooked food Raw or RAW may also refer to: Computing and electronics * .RAW, a proprietary mass spectrometry dat ...
format (if supported), white balance can be arbitrarily changed in postprocessing as well, so white balance bracketing is particularly useful for reviewing different white balance settings in the field. In contrast to manual white balance bracketing, which requires the photographer to take multiple shots, automatic white-balance bracketing, as it is implemented in many digital cameras, requires a single exposure only.


ISO bracketing

ISO bracketing is a form of simulated exposure bracketing in which aperture and shutter speed (thus depth of field and motion blur) remain constant. The brightness levels in this case are only altered by increasing or decreasing
gain Gain or GAIN may refer to: Science and technology * Gain (electronics), an electronics and signal processing term * Antenna gain * Gain (laser), the amplification involved in laser emission * Gain (projection screens) * Information gain in de ...
, or amplification of the digital signal prior to the conversion to an image file such as a
JPEG JPEG ( ) is a commonly used method of lossy compression for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and imag ...
or
Tagged Image File Format Tag Image File Format, abbreviated TIFF or TIF, is an image file format for storing raster graphics images, popular among graphic artists, the publishing industry, and photographers. TIFF is widely supported by scanning, faxing, word process ...
(TIFF). This type of bracketing must be performed with the camera in Manual mode but is easy to implement simply by shooting a single properly exposed image in RAW and applying exposure compensation in post processing. This is analogous to "pushing" or "pulling" in film processing, and as in film processing, will affect the amount of "grain" or
image noise Image noise is random variation of brightness or color information in images, and is usually an aspect of electronic noise. It can be produced by the image sensor and circuitry of a Image scanner, scanner or digital camera. Image noise can also ...
. It is also possible to apply a type of ISO bracketing which brackets the signal gain while maintaining a constant level of brightness in the finished photograph. In this case the exposure compensation (EV value) setting remains constant while bracketing the ISO value in Av, Tv, or P mode, which will have a corresponding effect on the shutter speed, aperture value, or both. This form of ISO bracketing could potentially affect not only image noise, but also depth of field and motion blur. In-camera
automatic ISO bracketing Autobracketing is a feature of some more advanced cameras, whether Photographic film, film or digital cameras, particularly single-lens reflex cameras, where the camera will take several successive shots (often three) with slightly different settin ...
is uncommon and therefore must usually be performed manually.


See also

*
Autobracketing Autobracketing is a feature of some more advanced cameras, whether film or digital cameras, particularly single-lens reflex cameras, where the camera will take several successive shots (often three) with slightly different settings. The images m ...
*
Exposure fusion In image processing, computer graphics, and photography, exposure fusion is a technique for blending multiple exposures of the same scene (bracketing) into a single image. As in high dynamic range imaging (HDRI or just HDR), the goal is to capture ...
, to merge images of different intensities *
Focus stacking Focus stacking (also known as focal plane merging and z-stacking or focus blending) is a digital image processing technique which combines multiple images taken at different focus distances to give a resulting image with a greater depth of fiel ...
, to merge images of different foci


References

{{reflist Photographic techniques