PHOTOGRAPHY LESSON

ONE of the most common questions about photography is why a beautiful sunset over a foreground of bush whose leaves are painted gold by the last rays of the sun can’t be adequately captured by a camera. The human eye can see about 24 stops of light (stops are a photographic measure of light – the f4, f5.6 you may have seen on your camera, and each stop ‘sees’ twice as much light as the stop before it). The human eye almost instantly adjusts subconsciously to see detail in dark shadows and the bright sky at the same time. A camera can ‘see’ about 12 stops, so it is only half as good as the eye and it only has one exposure (not the variable exposure our eyes provide) perhaps capturing the bright sky but leaving the shadows solid black and featureless, or detail in the shadows but the sky white and without detail. Modern cameras try to get around this problem by using HDR (High Dynamic Range) where the camera takes three images at different exposures and combines them into one. The resulting images are usually not perfect but certainly better than nothing – and getting better as technology improves. Software like Photoshop can tease detail out of shadows or can combine two or more photos separately exposed for the sky and the shadowy foreground. But, before the images are combined, they usually need processing in Photoshop for a range of colour and detail to replicate the scene as it appeared to the human eye.