Buchanan Studios Blog

news and events from Buchanan Studios

Posts Tagged ‘term

Technical Photographic Term of the Week: Density

leave a comment »

Density is the opacity of a particular area of an image.  In a positive image (prints, transparencies, digital displays) a dark shadow would be said to have a high density. On a negative, bright highlights are described as having high densities. Density is sometimes used to describe the overall exposure of a particular image (IE a light image would have low density.)

Written by stevebuchanan

March 28, 2012 at 10:19 am

Photographic Term of the Week: Dynamic Range

leave a comment »

Dynamic range is the difference between the brightest and darkest portions of any given scene. Photographic systems have limited ability to capture dynamic ranges, therefore it is important to manage the dynamic range within a scene by manipulating lighting and/or composition.  For example… an scene lit with only sunlight on a clear day may have a dynamic range of 20 stops, which is beyond the range of currently available systems in a single exposure (multiple exposure HDR notwithstanding.) Therefore it will be necessary to alter the existing dynamic range of the scene by adding supplemental light or other methods of reducing the scenes native dynamic range – or accept the scene will have some areas that are too bright and/or too dark to be fully represented in the image.

Written by stevebuchanan

March 16, 2012 at 5:03 pm

Photographic Term of the Week: Depth of Field

leave a comment »

Depth of Field is the range of sharp focus within an image. Measured in distance from the focal plane, depth of field (of DOF) is affected by many factors. Key factors being…

1. Aperture (f/stop.)  The smaller the aperture (higher f/number) the greater the depth of field, or more in focus.
2. Focus Distance. The farther the primary focus distance, the greater the depth of field.
3. Focal length of lens. The shorter the lens (lower focal length) the greater the depth of field.

By manipulating these factors the photographer can adjust the depth of field to suit their needs.

Many lenses have a printed DOF scale on the lens barrel to aid the photographer in determining how deep the field of focus will be. It’s worth noting, however, that there is no agreed upon standard for what constitutes sharp focus. Therefore scales will differ from manufacturer to manufacturer. Further complicating matters is the fact that in today’s world of different digital sensors within the same platform of lens mounts, a DOF that may have been acceptable with one camera body, may not be on another higher resolution body. Nonetheless, the optical principals of DOF remain the same across all lenses.

Written by stevebuchanan

March 2, 2012 at 12:23 pm

Photographic Term of the Week: Camera Raw

leave a comment »

Camera Raw, or RAW format is a digital storage format for images captured with digital cameras. RAW files have the advantage of containing all of the data captured by the camera, before any digital processing. RAW files are also sometimes referred to as digital negatives. (Adobe’s DNG format is a type of RAW file.) Most end uses of digital images are capable of displaying no more than 8bits of information per color, whereas most digital cameras can capture far more (10, 12 even 16 bits.) Capturing images in RAW format allows the photographer to manipulate the image in post production with less of a chance of technical flaws becoming apparent in the final image.  (IE, more manipulation of color, exposure, density etc – with less digital artifacts like noise and banding.) After post production on the RAW file is complete, the photographer can then convert to a more standard file format such as TIFF or JPEG.

Drawbacks to using RAW include…
Increased file size over JPG
Proprietary format from manufacturer to manufacturer
Specialized software often needed to read and process RAW files.

Written by stevebuchanan

February 24, 2012 at 9:59 am

Photographic Term of the Week: Additive Color

leave a comment »

Additive color is the process of creating colors by combining light. IE, white light (neutral) would be created by combining equal amounts of red, green and blue light. Conversely, subtractive color is the process of creating colors by filtering reflected light. IE, black (neutral) would be created by filtering equal amounts of cyan, magenta and yellow. Additive color is used in transmissive displays (televisions, monitors, backlit transparencies) subtractive color is used in reflective displays (prints)

Note regarding subtractive color in commercial printing: Ideally the combination of C,M,Y inks would produce a perfect black, but in practice they do not. Therefore the addition of a fourth black ink (referred to as K) is used.

Written by stevebuchanan

February 17, 2012 at 9:41 am

Photographic Term of the Week: Barn Doors

leave a comment »

Barn Doors are light modifiers added to an artificial light. Usually consisting of two or four independently hinged cards or flags used to block light from a particular portion of a scene.

Written by stevebuchanan

February 10, 2012 at 9:38 am

Photographic Term of the Week: Bokeh

leave a comment »

Bokeh refers to the portion of an image that is rendered out of focus by the lens, or more specifically, the way a lens renders those out of focus portions. Various factors play into a particular lens’ bokeh affect and it’s quality. Bokeh is most visible in images that have a shallow depth of field, as those images have large portions of the image out of focus. Whether or not a lens is said to have “good” or “bad” bokeh is a function of its particular design, specifically aperture blade shape and optical characteristics.

Portion of an image showing bokeh

Written by stevebuchanan

February 3, 2012 at 10:34 am