Initial Image - Highlight Just Clipping. The image has some interesting features. It shows a road works operation with individuals and unfortunately equipment changing position. This latter situation is out of my control and in any case is not relevent to the exercise. What is relevent is that the image contains various areas of potential highlight clipping. The sky, which contains a variety of tones; the white and silver of the various vehicles and possibly the bright yellow trailer in the foreground. The Just Clipping image was generated by spot metering a bright area of the sky, changing the camera setting to 'Manual' and while retaining the aperture setting of f8 as a constant, decreasing the shutter speed by half a stop until highlight clipping was indicated on the camera screen. The final image was obtained by adjusting the speed up and down until the final compromise was found. The final setting was 1/100 @ f8. ISO 200. During this exercise over exposure showed, as expected, clipping initially in the sky then as the exposure increased, on the van and car bodies and eventually on the yellow trailer. Histograms of this image showed a spread over the whole range of tones with a very small amount clipped on the right hand side of all channels. 
Plus One Image. There has been some movement of vehicles and bodies. Clipped areas have enlarged considerably in the sky particularly around the original clipped area but also along the horizon. Loss of a small amount of clipping is evident on the top corner of the van. Clipping with this exposure has not reached the other highlight areas. Camera setting – 1/50 @ f8. ISO 200.
The enlarged view around the original clipped area shows a pink colour fringing. Does this indicate that the other two complementary channels, Blue and Green, are clipped more leaving a version of the Red? Some research has not enlightened me!
Examination of the enlarged clipped area shows entire loss of detail in the centre of the patch surrounded by and including the pink fringe. No detail exists until outside of the pink area. There is no sharply defined edge of the clipped area. Even within the clipped patch there is still a faint pink tinge.
The use of the Recovery slide up to 25% almost eliminates the clipping in the sky leaving an unobtrusive small amount. Any further increase while showing more detail darkens all light areas so reducing contrast in the image.
Minus One Image
To change Minus One, Minus Two Minus Two Image
and Minus Three images so as to
equate to the Just Clipping original, one
would think that using the Exposure slide
in Raw set to +1, +2and +3 would solve the issue.
The Exposure slide required 1/2 stop than the
under exposed value plus a slight adjustment
of the Recovery slide. This did not lift the
shadow clipping. Use of the Black slide
was required for this and finally a
discrete use of the Brightness adjustment
to raise it to the original.
Minus Three Image
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