For a long while now, we’ve been keenly aware that highlights in skin tones and light-colored fabrics have been difficult if not impossible to recover in post, leading us to re-examine our ETTR method. After watching a video by Gerald Undone, we tried using two zebra settings, aiming for an ETTR of only +1.66 stops – well below what we were accustomed to. However, whereas using zebras had for years been liberating, freeing us from the drudgery of having to schlep around a monitor just for the waveforms, the new routine was beginning to make shooting an unbearable drudgery, prompting us to write only a couple weeks ago
Using zebras can be a real nuisance! Let’s say that in the menus, I’ve got zebras Custom 1 set to 55% for 18% gray (for an ETTR of +1.66 stops) and Custom 2 Lower Limit set to 94% (the limit before clipping occurs with S-Log3). Each time the lighting conditions change, I’ve got to pass the X-Rite ColorChecker to the model, take a reading of the gray card, then dive into the menus and switch to Custom 1 to check for highlight clipping. However, because it’s an exercise in futility trying to see zebras with Sony’s ludicrously subpar low resolution LCD, it’s necessary to engage magnification; but wouldn’t you know, it’s no longer possible to adjust zebras while the image is magnified, necessitating doing this dance between the magnifier and zebras – by which time the light has probably changed and the model has collapsed out of despair.
Anyhow, words can’t express the exhilaration we felt – after a half year of setbacks – upon discovering the secret to taming those highlights and extracting the full 12-1/2 tasty stops of dynamic range out of our a7s III. It also appears that ugly banding, which damaged many of our previous videos, is much less of an issue. The secret, of course, is shooting ProRes RAW HQ using the false color of the Ninja V as a guide, transcoding to ProRes 4444 in Apple Compressor, then grading in DaVinci Resolve. Yet another benefit is being able to get a vivid, contrasty image in seconds using just the global wheel of the HDR palette rather than having to yank the highlight, midtone and shadow wheels in Final Cut Pro every which way just to normalize the exposure (see note below). And don’t forget that getting the exposure and contrast right is also going to impact your colors.
One striking difference between SDR and HDR is the amount of information contained in overexposed areas. In practice however, an exceedingly small number of bright pixels account for a disproportionate quantity of the dynamic range. So even while infrequent, they constitute the very quintessence of high dynamic range. Which explains our disappointment, when watching HDR content, at seeing clipped highlights where one expects to see detail.
Note: “It is also worth bearing in mind that the traditional lift, gamma, and gain operators are particularly unsuitable for acting on ST 2084 image data, where 0-1 represent zero to 10 000 cd/m2. Highlights, in particular, can swing uncontrollably into extreme values as a result of small changes. Modern grading systems offer alternate grading operators tailored to the needs of HDR grading”. – Nick Shaw