Panasonic AG-DVX200 Tech Brief - Volume 6 - V-LOG L Based Production - Page 7

camera is capable of seeing and rendering brightness above 90% re ectance, as illustrated by the fact that 90% re ectance is mapped to 61 IRE, but in VLOG-L the camera can resolve up to 80 IRE. at translates into approximately 1.5 stops of exposure latitude above 90% re ectance before reaching maximum clip. In VLOG-L, the curve is laid out so that there are 8 stops below middle gray, and 4 stops above middle gray. You can, of course, choose to modify that by underexposing middle gray some; if you underexpose by one stop, you'll then have 7 stops below middle gray and 5 stops above it. In all cases you'll get 12 stops of dynamic range; the recommended allocation is for middle gray to be at 42 IRE with 8 stops below and 4 stops above, but you can shi that on an as-needed basis, so long as you account for it in post. is is one reason why it is such an excellent idea to shoot a standardized test chart at the head of every scene, so the colorist knows exactly what the intended exposure was and can account for any individualized decisions that were made on a scene-to-scene basis. e technique of exposing towards middle gray is similar to conventional video gamma exposure, where you frequently will have some typical "anchor points" in your exposure plan (such as having Caucasian skin highlights peak at about 70 IRE on a standard video gamma, and keeping your highlights at or below 100 IRE). Keeping skin tones comparable shot-to-shot makes matching footage easier in post, obviously; keeping middle gray levels constant will make matching VLOG-L footage easier in post too. Exposing for a logarithmic gamma isn't necessarily as simple as putting an 18% gray card in the scene and exposing it for 42 IRE. It can be that simple, if you want it to be, but there are steps you can take to perhaps improve the images the camera generates. e question is usually one of balancing noise versus retaining highlights. As with all digital camera sensors, the darkest regions of the image are typically the areas that show the most noise. Exposing To e Right is a technique designed to li the image up out of the noisy area and have it render in the "sweet spot" of the sensor's exposure range, which you can then drop down to proper exposure in post-production while avoiding some of the sensor noise. And that's a valid technique, but it does sacri ce some of the sensor's dynamic range (dropping the footage back down crushes o the darkest tones), and it can result in highly inconsistent midtones from shot to shot. When you overexpose the image, you also run the risk of clipping the highlights earlier. When you properly expose the image, you may maintain the highlights but you may also encounter some noise in the shadows. If you are lming a scene where there are a lot of very bright highlights, you may actually need to underexpose the scene to preserve those highlights, even if it means pushing your subject down into the noisier darker sections of the sensor's range. Or, you may just have to bite the bullet and accept that sometimes highlights clip and there's nothing you can do about it - or, rather, there may be nothing that you should do about it; compromising the quality of the main subject in a quest for preserving highlights may not be an acceptable tradeo in some cases. ere is no one overall "right" answer, there is only a question of your priorities - if you cannot stand clipped highlights under any circumstances, maybe you should use ETTR, understanding that in the quest to preserve every bit of highlight detail you might end up underexposing the image, resulting 7