Every photograph we take is a black and white photograph! A color photograph is just a black and white photograph overlaid with color information. Highlights give the photograph life and sparkle, the mid-tones mood and atmosphere, the shadows strength and structure. Shadows are the foundation tones of all photographs on which everything else is built. The ability to create tonally rich black and white photographs underpins every photograph – if you want to create beautiful fine art landscape photography. There is almost no true, solid, pure black in real life. Why then is it so common to see such very black, solid, filled-in shadows in photographs? Good shadow tones give the print a luxury richness and yet in fact, contain very minimal 100% pure black tones; just enough to give the picture a solid anchor. Here lies the core, fundamental conflict between what we want and what science gives us. A camera conflict we must understand.
Science could not be better designed to destroy the shadows; by default, the camera will do the most perfect job, at destroying shadow information and tonal separation – detail. Understand why and you can then overcome the conflict with a solution, ignore it and you are at the mercy of the camera change and bad shadow detail. An explanation of the conflict can be found when we look at the camera response curve. The camera response curve is a graph showing the relationship between incoming light and the tonal value the camera creates for that light. The camera response curve covers all the dynamic range from pure white to black and all cameras, have almost identical camera response curves; because all cameras are dictated by the same science. Camera manufacturers are aware of the shadow defect in the camera response curve; which is why they add ‘in-camera’ software to artificially counteract and mask this defect.
However, there is a fundamental quality difference between software manipulated, enhanced shadow tone and natural ‘in-camera’ shadow tone. Never make the mistake that they are the same and never rely on your ‘in-camera’ software or post-processing editing software to create, good, rich shadow detail. What does the camera response curve tell us? We can divide the curve into three key points; highlights, mid-tones and shadows. If we overexposed the highlights, they turn off like a light switch; there is no further ‘hidden’ information we can use for rescue later. If we anchor the exposure on recording the highlights, then the mid-tones are recorded about two stops darker than reality. The curve between the highlights and mid-tones is straight, but steep; meaning the camera gives more contrast and separation to all the tones above the mid-tones. From the mid-tones to black, the graph is a shallow curve that flattens out as it gets darker.
The darker the shadow tone is below mid-grey, the more compressed together the shadow tones become; this creates microscopic separation. Muddy filled in tones with little visible detail. The ‘in-camera’ solution and then post-processing solution is to stretch these existing tones apart; making them brighter with a curve adjustment. However, as we stretch the tones apart, data gaps are created between what the camera recorded and what we see on the monitor. All these data gaps must be filled in with artificial data – tone created by the computer. Interpolated data, the computers ‘best guess’ at what the missing tone should be. A computers ‘best guess’ is nowhere as accurate as recording real tones ‘in-camera’. Tones make detail, detail is made up of thousands of subtle tones. In comparison, interpolated tones are heavy handed solutions, heavy tonal blocks – better than nothing but come with a great price; the loss of subtle detail.
The solution, if we bracket, massively overexpose the shadows, we record the shadows brighter in the camera. We move the shadows up the camera response curve into the healthy mid-tone, straight line part of the camera response curve that naturally creates great tonal separation, contrast and definition ‘in-camera’; detail. Because all the tones have now been recorded naturally bright and therefore contain great tonal separation, we do not need to brighten them with an adjustment curve; therefore, we never create a situation where data gaps are created requiring interpolation to solve. The result is great shadow separation with great detail. If the shadows are too bright, we can darken them, in effect we discard the excess camera data. Darkening does not create data gaps. so does not require the damaging interpolation solution. The moral is; ‘if we brighten the shadows, we destroy quality, if we darken shadows, we do not destroy quality’.
Science hits us a second time in ruining the shadow quality of our photographs; noise. All digital cameras create noise in the image. We have one advantage; noise is a uniform amount, not a variable. Dark tones have a high proportion of noise, bright tones have a low proportion of noise. Imagine this analogy of a baker. Every time the baker bakes bread, science dictates the very first loaf of bread will be burnt and unusable. If he bakes two loaves of bread, then 50% of his loaves are wasted. If he bakes a hundred loaves of bread, then only one-hundredth of his loaves are wasted. The more he bakes; his wastage is proportionally less. The brighter we expose shadows, the less noise they proportionally have. This means rich and milky smooth shadow tones, full of unbroken fine detail. Think of the bottom of the curve, as the bottom of a pond; where all the sludge lives – avoid any tones made from this part of the curve in your photographs.
The camera histogram is God! Every pixel of the photograph is represented in the camera histogram. Starting with an underexposed image, as we brighten the exposure the histogram moves to the right; redistributing the pixels to reflect the tones of the exposure. The histogram pinned at the corner; the black point. The histogram is a very sharp, vertical ‘pyramid’ shape. As we increase the exposure, the sharp ‘pyramid’ falls over, gradually taking on a very smooth ‘hump’ shape; still pinned at the black point. Increase the exposure more, the shape of the histogram remains constant – but ‘pulls away’ at the black point; a small gap appears in the left corner. This is now your optimum exposure for maximum shadow quality and detail. Imagine the histogram, equated to taking off in an aircraft. Steep histogram, brutal take off. Smooth histogram, enjoyable take off. Same with tone; a smooth histogram means smooth, rich tone full of detail.
Exposures are the digital assets we require to create our photograph in Photoshop. There are three types of Photoshop assets we need to capture. The base image is our best attempt to get the perfect photograph in one single frame. This becomes the final photograph after additional assets are added. Technical assets, principally bracketed exposures as discussed and artistic assets where the light strikes subjects in the scene not captured in the base image; light falling on the surrounding hills or secondary heroes for example. The more artistic assets, the more creative freedom we have later in Photoshop retouching. This process requires every exposure to align up ‘pixel-perfect’ in Photoshop. The ability to align multiple exposures in Photoshop is central to my whole photography technique but opens a whole new world of creative possibility. This also allows us to shoot any contrast level or situation without resorting to HDR software.
Tonal quality begins at the camera. How we expose our photographs makes a tremendous difference to the quality, the richness of tone in our final photograph. If we do not get this correct at the camera, it’s too late when at home. Cameras do not and never will record, what we see. Equally, cameras have built in presets. We need to set all these to zero, so the camera does not manipulate the raw material, our digital assets; we want to retain total control of the quality ourselves. So, when do you leave? Generally, when you are cold, wet, bored and depressed or talking to the sheep because you’re so lonely. When God looks down and sees a photographer, he rubs his hands with a big grin and says ” I’m going to have fun today”. He is going to play with you! Just after you leave, the sun comes out like a Rembrandt painting, but stops just as you run back to capture it! When do you leave? When you have all the digital assets you need.
David Osborn | Professional Photographer, London, 2020