Composition is not independent of exposure

Here’s a non-obvious thought: composition should be linked to exposure. On the face of it, this does not make any sense at all: how can something which is a technical property of the camera (exposure) control what we do with an artistic and subjective (composition) one? There are two things we need to take into account here. Firstly, our eyes and our cameras work differently, so there will be some gaps in translation. Secondly, photography – composition and all – still ultimately boils down to light, since a photograph is nothing more than a record of luminance, color and spatial position in two dimensions. The starting position is what changes the appearance of the recording even if everything else in the scene is static.

I’m going to start with the first point: our eyes and cameras work differently. This has two consequences for photographers: since we only see one exposure, we actually need to either imagine how a darker or lighter scene would look, or use the camera’s live preview to see it. Here, mirrorless obviously has an advantage: the live image which you use to compose accurately reflects the final image – any sort of optical viewing system does not; you see the exposure determined by your eyes. This complicates things further because there is no such thing as over or underexposure unless there is very, very little or an enormous amount of light – the rest of the time, our eyes adjust automatically, and almost never clip.

On top of that, a photograph has a hard, defined edge. The human field of vision does not – you can’t concentrate your attention on the edge of your field of view because your eyes will move, and then that former ‘edge’ will become the new middle. The closest you can get to visualising this is staring in the middle and moving your hands slowly into the periphery of your vision – they never suddenly disappear, but rather become less distinct as you move them outwards. (We see and interpret a continuous field of view because our eyes are always scanning.)

In summary, a) it is difficult for our eyes to simulate a different exposure; b) we aren’t really conscious of the edges most of the time. Park that for a moment.

I think it’s not difficult to understand that by changing the amount of light on a scene, we change what is visible: turning on the lights in a dark room reveals the contents of the shadows. Unfortunately, it is not so easy to visualise what an increase in intensity – but no change in direction or diffusion – will do. (Turning on the lights changes both direction and position of the source, not to mention color temperature, intensity and throw.) Regardless, the fundamental tenet is the same: what is visible has changed. And since what is visible in the frame has changed, we therefore need to take this into account when composing with a different exposure to what we see with our eyes.

Let me rephrase this slightly: if we intend to present the scene with a different exposure to what we see – whether this is local or global, high key or low key, then we need to take this into account when considering which compositional elements are visible and prominent, and adjust the balance of the frame accordingly. Note that this is not limited to just a change in global exposure: if you change contrast, that also affects what is visible in shadows and highlights; more contrast will increase prominence of certain areas because fine tonal differentiation will disappear.

Complicating things further is the necessity of exposing to the right to maintain optimum image quality: the highlight areas contain the most data and therefore least noise. Even if you intend to make a low key image, you’ll still want to expose to the right (and start with a much brighter image than the output) to preserve as much latitude for smooth shadow and highlight rolloffs as possible. The easiest way to take this into account if you can preview exposure is 1) compose with an accurate exposure preview, then 2) without moving the camera, take the shot but exposed to the right. Make a mental note of your final intended exposure after postprocessing, or actually shoot 1) and use it as a reference. (The Venetian Cinematics were shot this way, and though the final output is extremely low key, the starting point looked almost like daylight.)

Let’s look at a couple of examples.

These two images are different in both exposure, and resulting mood. All that has changed between them is exposure; I have optimised contrast in both cases with a curve but made no local adjustments otherwise. From an idea/intent point of view, the darker of the two is somewhat ambiguous and more dramatic; the bassist is an idea of a generic bassist rather than a specifically identifiable individual, as in the brighter image.

However, it’s also clear that the darker image feels as though it is biased towards the left – the right portion is dark and ambiguous. It doesn’t have a particularly defined shape suggestive of something missing or open to interpretation by the audience: it’s just imbalanced. This is not surprising given that the image was exposed for and composed for the lighter composition: you can see in that version, the background has been filled with low-contrast and darker elements to provide context – a second musician, the accoutrements of a stage, light beams. Yet since these elements are darker, smaller, out of focus and therefore less visually prominent, they do not stand out as primary subject in the same way the main guitarist does. In actual fact, even this brighter exposure is somewhat darker than reality as there were even more extraneous elements visible in the edge shadow areas – those added nothing to the image other than a degree of messiness; at the time of composition I determined that a slightly darker exposure would be needed to clean up the edges.

Here is an example where the original image was composed to be low key and be slightly brighter than the actual scene as perceived. There is a leading line created by the form of the foreground buildings drawing the eye from lower right to mid-left; the anchors are the lit windows. Though these are on the far left side of the frame, there is a bright (but spatially larger) building towards the upper right to prevent the audience from wandering out of the left side of the frame. It is less visually prominent. On top of that, there are small bright details of increasing frequency as you move upwards through the image – this layering creates a sense of relative scale and distance receding into the background.

A darker – in this case true to life – exposure is clearly biased to the left again; the lit windows are really the only elements that stand out, and worse still, they form a sequence that pulls you out of the frame. The right side of the image does not hold sufficient visual prominence to counterbalance.

Curiously though, an even brighter exposure has similar balance to the first (intended) image, though what is lost is the mood and dynamic – there is no more ambiguity or room for interpretation in the shadows; the highlight anchors do not stand out as much because their relative contrast to the rest of the frame is lowered. It is unclear if this is meant to be night or evening or very late afternoon.

You’ll note that for both of these examples, overall global dynamic range/contrast is pretty high: it’s possible to clip highlights and/or shadows depending on your hardware and postprocessing. I chose these deliberately because the effect of exposure on compositional balance is far more pronounced than with an image whose tonal range fits nicely within the capture and output dynamic range; the perceptual shift would not be as obvious. However, it’s worth noting that it’s possible to make images that feel balanced and ‘complete’ in each exposure case presented here: the cameras needs to be panned or tilted accordingly to take into account the now-empty areas. We’ll discuss the concept of balance in more detail in a future article, but in the meantime, make your final exposure choices conscious ones. MT

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