PROJECT 1: EXPOSURE
1. Set your camera to any of the auto or semi-auto modes. Photograph a dark tone (such as a black jacket), a mid-tone (the inside of a cereal packet traditionally makes a useful ‘grey card’) and a light tone (such as a sheet of white paper), making sure that the tone fills the viewfinder frame (it’s not necessary to focus). Add the shots to your learning log with quick sketches of the histograms and your observations.
I shot in program mode in daylight white then black then grey card:
Yes I was surprised that the resulting images were very similar as are the histograms. However I understand that by default as the camera assumes that the desired brightness of an image should be medium grey (18% grey) and therefore adjusts other setting to achieve this.
2. Set your camera to manual mode. Now you can see your light meter! The mid-tone exposure is indicated by the ‘0’ on the meter scale with darker or lighter exposures as – or + on either side. Repeat the exercise in manual mode, this time adjusting either your aperture or shutter to place the dark, mid and light tones at their correct positions on the histogram. The light and dark tones shouldn’t fall off either the left or right side of the graph. Add the shots to your learning log with sketches of their histograms and your observations.
In manual mode (which disconnects the aperture, shutter and ISO as they’re no longer linked, you can make adjustments to any one of them without affecting the others), I set the exposure correctly for the grey card and then altered the shutter speed whilst shooting the black and the white cards to maintain the marker on the light metre in the middle as it was for the grey:
The grey histogram peaked in the middle, and the black and white histograms spread a little more respectively to the left and the right. So it is possible to maintain a correct exposure by adjusting the shutter speed or aperture and maintaining the central light metre marker in the centre.
Next I repeated the exercise but shooting in manual mode adjusting the exposure correctly for the grey card so that the histogram would peak in the middle. Shooting the black then white I kept the camera exposure settings in manual mode the same:
This resulted in a correct recording of the black and white images and the histograms to appear as you would expect, the white peaking towards the right and the black peaking towards the left. This is because if the grey card is a true 18% grey then this should be the average and ensure that the black is true black and the white true white. Although my grey card wasn’t a true 18% grey it did give a fair average exposure setting and resulted in more realistic images and histograms.
The results would have been different if I had used an external light meter as it would measure the incident light rather than reflected light, so the colour tones would be exact.