What is dynamic range? Understanding the term and its applications

In photography, whether or not you can accurately capture the contrast between light and dark has a significant impact on the final result. One key term related to this is "dynamic range." In this article, we will explain the meaning of dynamic range and how to apply it in photography.

What is dynamic range?

Dynamic range refers to the range of brightness from the darkest to the brightest parts that a camera can record in a single shot.
The human eye has an incredible ability to immediately detect subtle variations in light and dark, even in bright or dark environments, helping us perceive our surroundings. On the other hand, the dynamic range of digital cameras is narrower than the human eye's, and light that exceeds this range can result in overexposed highlights or underexposed shadows. This is especially noticeable in subjects with a large difference between light and dark, where the subtle details are often lost.
For example, when photographing a scene with strong backlighting on a sunny day, the sky may become overexposed, or the buildings in shadow may become completely black. However, if the camera's dynamic range is wide enough, you can capture rich gradations from the dark areas to the bright areas, even in such challenging conditions.

The relationship between sensor size and dynamic range

The size of a digital camera's image sensor also affects its dynamic range. Generally, the larger the sensor, the wider the dynamic range. Full-frame sensors, in particular, have larger pixel areas, allowing them to capture more light information. This helps preserve detail in both the dark and bright areas while reducing noise in the shadows.
Recent advancements in image processing technology have significantly improved the dynamic range even for small sensors, such as those in smartphones. However, it is still generally true that larger sensors provide better dynamic range.

Dynamic range and tonal expression

A term related to dynamic range is "tonal range." While dynamic range refers to the "width" from the darkest to the brightest part that can be recorded, tonal range refers to the gradual changes in brightness within that range.
Modern digital interchangeable-lens cameras can record 14-bit RAW data, theoretically allowing for 16,384 levels of tonal expression. The overall "width" of dynamic range and the "smoothness" of tonal range within that width both influence the contrast and three-dimensionality of the photo.

What happens when You exceed the dynamic range? – Highlight clipping and shadow clipping

When light exceeds the dynamic range of the camera, the camera can no longer distinguish between the differences in brightness. For example, when there is too much exposure, the bright parts can experience "highlight clipping," causing the loss of color, tonal detail, and texture in the image. Conversely, when there is too little exposure, the dark parts can experience "shadow clipping," making it impossible to distinguish fine details in the shadows.
To avoid these issues, it’s helpful to check the histogram during shooting and adjust the exposure so that the graph’s extremes don’t get clipped. If shooting in RAW, highlight and shadow clipping can sometimes be corrected in post-processing.

The relationship between dynamic range and ISO sensitivity

Dynamic range is also closely related to ISO sensitivity. Increasing ISO sensitivity boosts the sensor’s sensitivity, enabling you to shoot in low-light environments, but it also narrows the dynamic range. Generally, an ISO setting between 100 and 200 provides the widest dynamic range.
When shooting at high sensitivities, be mindful of highlight clipping and noise. If necessary, reduce the exposure slightly to preserve details in the highlight areas.

Utilizing dynamic range with RAW shooting

RAW is a data format that records almost unprocessed information captured by the camera's sensor, containing much more information than JPEG. In terms of exposure, RAW allows for exposure adjustments of about ±2 stops during post-processing, making it possible to retrieve details in the shadows or reduce highlight clipping that was not visible during shooting.
Additionally, because tonal range adjustments in RAW are based on the original image data, they minimize the loss of tonal detail that is common in JPEG files. While RAW files are larger and require more post-processing effort, saving in both RAW+JPEG format is a good option for professional shoots or situations where you cannot afford mistakes.

High dynamic range (HDR)

HDR is a technique that allows for a wider dynamic range than what a camera can capture in a single shot. HDR works by merging multiple photos with different exposures to represent a broader range of light and dark areas that cannot be captured in a single exposure.
Typically, HDR involves capturing multiple images with underexposure, correct exposure, and overexposure, then combining them to capture details from both the dark and bright areas. Try HDR photography for scenes with significant contrast, such as backlighting or nighttime shots. You can also create more flexible HDR images by using bracketing techniques, which will be discussed later.

Shooting subjects with a large contrast between light and dark

For scenes with large contrast, such as landscapes at dusk or backlit portraits, "bracketing" shooting is often used. This involves shooting multiple images at different exposures with the same composition, then later combining the photos to create a composite image. Specifically, RAW images are taken at underexposure, correct exposure, and overexposure, then combined in post-processing for HDR merging. This manual method offers more freedom of expression compared to auto HDR.
To brighten the subject, use spot metering. Spot metering allows you to set exposure on a specific point of the subject, helping you achieve a bright image of the subject.
Once your photography skills improve, consider using a graduated ND filter to adjust the brightness difference between the sky and the ground. Also, try shooting with high-key or low-key techniques to challenge yourself creatively.

Utilize dynamic range knowledge in photography

Dynamic range refers to the range of light and dark that a camera can capture in one shot. By utilizing RAW and HDR techniques, you can effectively capture subjects with significant contrast, even when the camera’s dynamic range is limited. Checking the histogram and adjusting the exposure during shooting is also an effective way to manage dynamic range. Apply this knowledge to challenge yourself in creating impactful and compelling photos.