In night videography, what is the primary technical reason for applying the 'expose to the right' principle when shooting in a Log/flat profile?

The primary technical reason for applying the 'expose to the right' principle when shooting in a Log/flat profile during night videography is to maximize the signal-to-noise ratio in the darkest areas of the image, thereby preserving shadow detail and minimizing digital noise. 'Expose to the right' (ETTR) is an exposure technique where the image is intentionally overexposed to gather as much light information as possible without 'clipping' the highlights, meaning without losing detail in the brightest parts of the scene. A Log/flat profile is a camera setting that records video with a significantly wider dynamic range, which is the difference between the brightest and darkest areas a camera can capture. This profile compresses bright areas and expands dark areas into the available digital data range, resulting in a desaturated, low-contrast, 'flat' image that is ideal for extensive color grading in post-production. Digital camera sensors inherently produce more noise, which appears as unwanted graininess or color artifacts, in areas that receive less light. The amount of noise is inversely proportional to the amount of light captured; less light results in more prominent noise. When shooting in low light conditions like night videography, the available light is scarce, making the shadows particularly susceptible to noise. By applying ETTR, the sensor collects more photons across the entire scene. This stronger light signal increases the 'signal-to-noise ratio' (SNR), which is the strength of the desired image information relative to the undesirable noise. A higher SNR means less visible noise. Crucially, Log profiles, while excellent for dynamic range, allocate a substantial portion of their available bit depth, which is the number of distinct light levels a pixel can represent, to the mid-tones and highlights to achieve their wide latitude. Consequently, the extreme shadows are represented by fewer digital values. If these shadow areas are underexposed, they are assigned very few bits and are heavily dominated by noise. By intentionally overexposing with ETTR, the shadow and mid-tone information is recorded with more light, pushing it into the higher, cleaner bit values of the sensor's output before any information is lost in the brightest highlights. In post-production, this slightly overexposed Log footage can then be 'pulled down' or darkened to the correct exposure. Because the initial capture had a much stronger signal in the shadows, the noise, which was recorded at a lower relative level, is also reduced when the image is darkened, resulting in cleaner, more detailed shadows compared to a normally exposed or underexposed image where attempting to brighten noisy shadows in post-production would only amplify the noise.