We took a closer look at the Canon Log and Canon Log 3 curves and what difference they make. This should start to explain why there are multiple Log options: you want to find a Log curve that's well suited both to the capabilities of your camera and to the scene you're shooting. ![]() This is less of a problem on higher-end cameras that shoot 10-bit footage (and so have 1024 values to share), but is worth considering if your camera only captures 8-bit Log, and hence has only 256 values available. If you try to share those values roughly equally between 11 stops of light, you retain more information about each one than if you try to squeeze 15 stops into the file. Your camera can only record a certain number of brightness values. The final consideration is data availability. A two-stop reduction in exposure means a two-stop increase in noise in all those tones that overlap with the standard color mode. If we assume the Log curve is designed to incorporate another two stops of highlights over what a standard sRGB JPEG would include, you'd need to reduce exposure by two stops to capture this additional highlight information. ![]() Canon Log 3's base ISO setting is rated as 800, to capture an additional stop. In order to capture around 2EV more highlights than a standard JPEG, it's supposed to be exposed as ISO 400 (rather than the ISO 100 that's the base setting for the Standard color mode). For a start, it would mean that the bottom three stops of your file would be a noisy mess, but it would also encourage you to use an inappropriate exposure.Ĭ-Log is designed to accommodate around 11 stops of DR. And there are a number of reasons why more is not always better.įirstly, there's simply no point using a Log curve that encodes 15 stops of light if you sensor can only capture 12 before the signal becomes indistinguishable from noise. More precisely, Log curves are designed to encode a pre-determined number of stops of light. In the previous section I wrote that Log curves are designed to retain similar amounts of information about every stop of light you captured. Colors are also desaturated, to reduce the risk of saturated parts of the scene clipping and hence losing flexibility when color grading. The simplest way to think of Log files is like JPEGs but with tone curves designed to share their data values out more equally between the number of stops you captured. ![]() Crucially, it tends to be relatively small, which is valuable in video: when you're measuring file sizes in data per second, then the clock is ticking from the moment you hit the button. Log is an attempt at a middle ground between these two: it's subject to a lot of the processing and compression that a JPEG file is, but has been expressly designed to retain enough information about the original capture to remain flexible. In stills photography we generally choose between JPEG files (a small and efficient compressed format but one that has limited editing flexibility), and Raw files (larger but retaining the greatest flexibility).
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