Saturday, 13 August 2011

Part 4 Light–Project:The Intensity of Light

Measuring Exposure 1
This first exercise is in two parts. The first was to produce a handful of photos in which the exposure settings have produced an image deliberately lighter (high key) or darker (low key) than the average setting  for the scene.
My first image was produced low key to emphasise the shadows projected by sunlight through a glass jug onto the worktop. The average (matrix) reading for the scene was 1/90s f5.6 ISO 200.

Looking at the image on the LCD screen of my camera, I determined that half a stop less exposure would result in a darker image but would retain the highlights.

7138: 1/90s f6.7, 200mm ISO 200 

I continued with this subject, this time changing the sharp focus from the glass handle to the shadow. Again to reduce the highlights I decreased the exposure. The intensity of the sunlight was changing constantly and for this exposure, in order to get the maximum depth of field I used the minimum available aperture. Again the image is considerably darker than the average, giving a low key image.
7139: 1/4s f32, 200mm ISO 200

My next attempt was to use candlelight to produce high and low key images. All images were taken at ISO800 using an incandescent B2 M2 setting to approximate the colour as seen by the eye. The camera was set on Matrix metering
7299: I established the average exposure for this subject with this image, as 1/30s, f5.3, 95mm. Even this ‘average’ exposure has extremes with the candle flame highlight burnt out.

7289: This high key image was exposed as follows: 1/3s, f8, 82mm. The flame and its reflection on the top of the candle are burned out but there is more detail of  the shadows and reflections on the background.

7292: Low key: 1/6s, f32, 60mm This image has only a small area of over exposure in the flame but very little detail in the shadows.

7324: Another low key image, this time taken with a sodium vapour lamp white balance setting to approximate the colour perception. The highlights are very close to being burned out but there are some details retained in the shadows: 1s, f22, 48mm.

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