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Agrégation 2001 : image analysis

Responsable : Professeur Marie-Madeleine Martinet

 
PHOTOGRAPHIC SETTINGS
Introduction / Shutter Speed
 

Shutter speed/apertureÞ depth of field

The choice is between high shutter speed (short exposure) combined with wide aperture, or low shutter speed (long exposure) combined with small aperture. The smaller the aperture (the higher the ‘f’ number), the longer the depth of field. The photographer will give precedence to one of these settings and the other will follow accordingly.

The major variations entailed by these changes in the exposure (which determine the photographer’s choice) will be on the rendering of the light effects on the objects.

Subject : waves on the beach at night

In these examples, it is supposed that the major effect was the contrast between two suggestions of movement
Short exposure (1/250 second) Long exposure (1/4 second)
Here the emphasis is on the enveloping night, with tiny light effects in sharp outlines The same subject with a longer exposure time: the emphasis is on the radiating effect of the reflected moonlight, which gives a soft-focus effect on the lit areas and lightens the colour of the dark areas
The photographer gave priority to the choice of shutter speed
In this case, the high shutter speed implied
  • a comparatively large aperture
  • a fairly small depth of field: the picture is blurred except on the waves, which focuses attention on them
Here, the low speed entailed
  • a smaller aperture
  • a high depth of field: the whole of the sea is clearly defined
 
 
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AGREGATION 2001
Image analysis
Landscape & Hypermedia
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