Saturday, 7 September 2013

"The Calling of Saint Matthew", Contarelli Chapel, Chiesa Di San Luigi Dei Francesi, Rome

Photograph Copyright ©2012 Loo Yen Yeo. All Rights Reserved.
Concepts: Chiaroscuro (Emphasising outline); Chiaroscuro (Secondary patterns); Exposure (High contrast)

Description: In "The Calling of Saint Matthew", Jesus (far right) calls upon Matthew, then Levi the tax collector (central figure behind the table), much to the surprise of the gathered.  This painting is a fabulous exemplar of Caravaggio's use of defining and emphasising the use of outline. The high contrast is used compositionally in directing the viewer's gaze - a similar effect can be achieved with the control of exposure (also to high contrast) in photography. Notice also the shaft of actual light coming into the chapel from above; a secondary reinforcement to the primary shaft in the painting.

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Friday, 6 September 2013

04.01 Chiaroscuro

Chiaroscuro is an Italian expression which can be translated literally as "light-dark" and arose out of its use in painting - where subjects in dark scenes were dramatically illuminated using shafts of light. Chiaroscuro, as an approach, is an effective means of providing the contrast essential to good composition where it:
  1. establishes tonal relationships;
  2. conveys dimensionality;
  3. determines compositional structure; and
  4. highlights areas of visual importance
Johannes Itten described chiaroscuro as "one of the most expressive and important means of composition" [in "The Photographer's Eye" by Michael Freeman (2007), page 110]. Compositional devices involving the application of chiaroscuro include:
  • crating ambiguity
  • emphasising outline
  • formation of primary patterns through caustics (i.e. reflected or refracted patterns of light)
  • reinforcement of secondary patterns e.g. sunlight dappling an already-dappled forest floor

Sunday, 1 September 2013

03.16 Exposure

Exposure, the amount of light allowed to impact photosensitive material for photographic reproduction, is often perceived to have a 'correct' role. There is an element of truth in this perception because of the technical limits set by:
  1. what is visible;
  2. the range of sensitivity of the photo-receptive medium (film or photo-sensor); and
  3. the expected appearance of the subject.
However, 'correctness' is modulated by the aesthetic considerations which do impact on how the technical boundaries are interpreted, for example: an over-exposed bleached look, or an under-exposed saturated image. The artistic interpretation of light is fundamental to the visual arts, and a solid understanding of the properties of light interpretation is core to the artist.

Exposure can concentrate or diffuse attention
The viewer's eye gravitates towards areas of perceptually 'normal' exposure from regions of underexposed dark and overexposed bright. Therefore:
  • higher contrast directs the eye; whereas
  • lower contrast lends the eye greater freedom to roam over the entire surface.
A photographic phenomenon which directs the eye is vignetting - wide-angle lenses can concentrate more light in the centre of the image field than the periphery i.e. exposure increases radially inward. Thus a vignette draws attention towards the centre of the frame.

Exposure affects the perception of form
High contrast conditions break up the visual continuity of form, whereas low contrast conditions preserve it. Take, for example, two horizontal elements: one above and at an angle to the other, illuminated from above. High contrast will mean that the continuous form of the lower element will be visually broken by dark shadow cast by the upper element. Low contrast would allow the lower element still to be seen as intact with the casting of a lighter shadow.

Exposure affects colour saturation
Over-exposure leads to desaturated (muted, bleached, washed-out) colours. The practice of exposing to keep the highlights within the range of the film - the dominant procedure still today - came about with the introduction of Kodak's Kodachrome film in 1935. Kodachrome was intolerant of overexposure, but rewarded underexposure with rich saturated colours. 'Exposing for the highlights' is still relevant in the world of digital photography because overexposure results in unattractive digital clipping. In this respect, digital sensors share similar limitations to Kodachrome (discontinued in 2009).

Graphical features of exposure
  • Silhouettes are the result from complete underexposure of the foreground, denying any foreground detail so that the outline of the dark shape tells the story.
  • Flares also deny detail, but are achieved through overexposure, and are commonly used to unify or increase the activity of a composition.