Excercise: Your camera's dynamc range

For this exercise I needed to find a scene with a distinctly high dynamic range. The best conditions for this are

• bright sunlight
• at least one brightly reflecting surface
• an area of deep shadow with a dark surface

Suggestions for the scene: a reasonable large (at least A3 size) piece of white card. This will be the highlight. Take, for instance, the front of a house that faces the sun, and open the front door, making sure that there is some dark surface visible inside. Make the ISO sensitivity at its lowest, then set the exposure and shoot so that there is just no highlight clipping of the white card.

Next, measure and make notes of the brightness of the white card and of two or three of the darkest shadow areas. I intend to use the following methods of measuring:

• spot metering
• if using a zoom, set at wide for the photo then zoom into the maximum and measure small areas
• walk close to the areas to measure so that they fill the frame

Make notes of the aperture/shutter speed and exactly which areas were measured. Open the image in Lightrom, zoom to 100% magnification and move to the white card. Using the pixel value sampler check the value of the white is only a little less than 255 in each channel.

Then move to the shadows, and adjust the brightness until the details are visible. Look for an area in which the level of apparently real detail and noise are competing with each other. Now calculate the range between the two ends in f-stops.

Although I haven't yet created the image specified in the exercise notes, I have taken the following image with the dynamic range required but didn't measure with a white card. On 100% magnification there is noise seen on the girl on the left's black top and also in the shadows on the right of the image, there is highlight clippings on the girl on the left's forehead and on the white of the box below her. If I had been taking this image for the exercise I would have adjusted the exposure to compensate for the highlight clippings. I do intend to make an image for this exercise when the weather conditions cooperate. ISO400, 51mm, f/7.1, 1.6 sec.