How natural light and meaningful darkness tell a story

Have you ever been somewhere, and want to take a photograph, and there just isn’t much natural light, or perhaps the light is only coming from a single source, such as a window? Are you tempted to use a flash? Well don’t even think about it, because doing so takes away from the story of what you are photographing. Usually this sort of scenario manifests itself inside historical buildings where there just isn’t much natural light, and in context, no artificial light. Think anything before electric lighting – houses, castles, outbuildings, etc. Photography in historical buildings can be burdened by a lack of light – but that’s how they were when inhabited.

I photograph mostly using natural light. I don’t like using a flash, because ultimately there are certain qualities of natural light that enhance the colours and aesthetics of an object or scene. I find flash light too harsh, even when used with diffusers. But that’s just me. Below is an image from the attic space of a building at the Voss Folkemuseum in Norway. The room contained some beds, and storage chests, so obviously it was used as a bedroom. The light streaming through the window is enough to bathe the room with enough light to show its use (typically windows would only have been installed where the light would be most concentrated, in this case south-facing). Notice the spinning wheel next to the window where the light is most concentrated?

An attic space in a building at the Voss Folkemuseum in Voss, Norway.

A lack of light often tells a story. It shows you what the space really was like for those who inhabited it long ago. Before the advent of electricity, most buildings relied on natural light during the day, and perhaps candle-light at night. Windows were small because glass was inherently expensive, and the more glass one had, the more heat that was lost in winter. If you were documenting a scene in a more archival manner, you might naturally flood the scene with artificial light of a sort, but historical photography should not be harshly lit.

Many historic buildings were built at a time of very little beyond natural light and candles. The light today is that very same light, and to bath it with artificial light would be unnatural. These nooks and crannies were never meant to be bathed in complete light. Consider the images below, taken at different folke-museums in Norway. The images are of cooking fires inside historic buildings, which had no openings except in the roof. The one from the Norsk Folkemuseum is Saga-Stau, a replica of an open-hearth house from about 3000 years ago.

The inside of an open-hearth house at the Norsk Folkemuseum
Eldhus (house with fireplace and bakehouse) at Voss Folkemuseum

On a bright sunny day, dark spaces are bathed in whatever available light is able to seep through every opening. In a dark space this light can often appear harsh, blinding window openings to the point where there is little cognition of the scene beyond the window. Yet it also tends to produce shards of light puncturing into a space. On clouded days, the light can be more muted. In the image below of the living space, the light coming through the window is harsh enough to produce highlight clipping of both the window frame and part of the table. However the light adds a sense of Norwegian Hygge to the entire scene. To light this scene with a flash would simply reduce the scene to a series of artifacts, rather than a slice of history.

An indoor scene at the Voss Folkemuseum.

the image histogram (v) – tone

In addition to shape, a histogram can be described using different tonal regions. The left side of the histogram represents the darker tones, or shadows, whereas the right side represents the brighter tones, or highlights, and the middle section represents the midtones. Many different examples of histograms displaying these tonal regions exist. Figure 1 shows a simplified version containing 16 different regions. This is somewhat easier to visualize than a continuous band of 256 grayscale values. The histogram depicts the movement from complete darkness to complete light.

Fig.1: An example of a tonal range – 4-bit (0-15 gray levels)e

The tonal regions within a histogram can be described as:

  • highlights – The areas of a image which contain high luminance values yet still contain discernable detail. A highlight might be specular (a mirror-like reflection on a polished surface), or diffuse (a refection on a dull surface).
  • mid tones – A midtone is an area of an image that is intermediate between the highlights and the shadows. The areas of the image where the intensity values are neither very dark, nor very light. Mid-tones ensure a good amount of tonal information is contained in an image.
  • shadows – The opposite of highlights. Areas that are dark but still retain a certain level of detail.

Like the idealized view of the histogram shape, there can also be a perception of an idealized tonal region – the midtones. However an image containing only midtones tends to lack contrast. In addition, some interpretations of histograms add additional an additional tonal category at either extreme. Both can contribute to clipping.

  • blacks – Regions of an image that have near-zero luminance. Completely black areas are a dark abyss.
  • whites – Regions of an image where the brightness has been increased to the extent that highlights become “blown out”, i.e. completely white, and therefore lack detail.

Figure 2 shows an image which illustrates nearly all the regions (with a very weird histogram). The numbers on the image indicate where in the histogram those intensities exist. The peak at ① shows the darkest regions of the image, i.e. the deepest shadows. Next, the regions associated with ② include some shadow (ironically they are in shadow), graduating to midtones. The true mid-tonal region, ③, are regions of the buildings in sunlight. The highlights, ④, are almost completely attributed to the sky, and finally there is a “white” region, ⑤, signifying a region of blow-out, i.e. where the sun is reflecting off the white-washed parts of the building.

Fig.2: An example of the various tonal regions in an image histogram

Figure 3 shows how tonal regions in a histogram are associated with pixels in the image. This image has a bimodal histogram, with the majority of pixels in one of two humps. The dominant hump to the left, indicates a good portion of the image is in the shadows. The right-sided smaller hump is associated with the highlights, i.e. the sky, and sunlit pavement. There is very little in the way of midtones, which is not surprising considering the harsh lighting in the scene.

Fig.3: Tonal regions associated with image regions.

Two other commonly used terms are low-key and high-key.

  • A high-key image is one composed primarily of light tones, and whose histogram is biased towards 255. Although exposure and lightning can influence the effect, a light-toned subject is almost essential. High-key pictures usually have a pure or nearly pure white background, for example scenes with bright sunlight or a snowy landscape. The high-key effect requires tonal graduations, or shadows, but precludes extremely dark shadows.
  • A low-key image describes one composed primarily of dark tones, where the bias is towards 0. Subject matter, exposure and lighting contribute to the effect. A dark-toned subject in a dark-toned scene will not necessarily be low-key if the lighting does not produce large areas of shadow. An image taken at night is a good example of a low-key image.

Examples are shown in Figure 4.

Fig.4: Examples of low-key and high-key images.