9 Jun 2010

Exercise: Control the strength of a colour

This exercise required 5 photographs taken with varying exposures of a block of strong colour showing the effect that changes in exposure have on the colour.  The task asks for shots to be taken at ½ stop intervals of increasing light and since my camera defaults to ⅓ stop settings I went into the custom menu settings to change this.  I also shot a couple of extra images at +/- 1½ for a better look at the effects.

Starting at -1½ stops the images go through the correct exposure to +1½ stops.

-1½ stops
 -1 stop

 -½ stop

OE (On Exposure)

+½ stop

+1 stop

+1½ stops

The shots shows a nice combination of textures and colour as well as shadowed and sunlit areas that allow us to notice the difference direct sunlight has on the shots.  The camera has done an excellent job of evaluating the correct exposure for the OE shot, despite the differences in light quality.  Our brief mentions the obvious difference that the changes of exposure have on the brightness of the images so I will restrict my comments to the changes in colour.

The first and most obvious difference is the change to the saturation of the colours.  The more underexposed the shot the more saturated the colours look and as the images move to over exposure the colours become more washed out and bleached.  I can measure the difference by using the eye dropper in Photoshop and take an RGB reading from the photographs.  The sunlit green goes from 70 at -1½ stops through 130 at OE to 160 at +1½ stop.  Visually this change can be seen as a move from a deep and luxuriously dark green to a delicate and pale green.

The exposure had made differences to the actual colour, as well as it's saturation.  Take the photos to a paint mixer and you would end up with completely different paint mixes to match each photo.  The shades of green also vary considerably within each photo depending on the quality of the light falling on different sections and the amount of light reflection that occurs with the different angels we can see.

From a personal point of view I have always liked the quality of slide film and in particular the E6 film, Fuji Velvia.  This film always had great colour saturation and using it over the years I got into the habit of shooting at -½ stops to enhance that look of strong, well saturated colours.  I still tend to shoot at -½ stop, particularly on a bright day when direct sunlight can rob the colour from a scene, partly to keep the colour saturation high but also to prevent accidental overexposure of bright areas.  I find it a lot easier to bring up underexposed areas of an image in Photoshop that attempt to recover detail from a blown patch.

No comments:

Post a Comment