Llaasseerr Posted June 14, 2022 Share Posted June 14, 2022 7 hours ago, OleB said: Have investigated this further. Look what I have found in regards to the fp behavior in RAW on the Atomos. Monitoring of RAW input in: - Native – Linear to VLog for use with 3D LUTs – can use any existing VLog LOOK LUTs - Rec709 – to view RAW input in SDR up to 6.7 stops of dynamic range - HLG – to view RAW in HLG with up 10.5 stops of dynamic range - PQ – to view RAW in PQ/HDR10 with up to 10.5 stops of dynamic range, for scenes with extended spectral highlights. Am about 99% sure that the camera is showing Vlog when switched to native. OK there you go. So yes it's confirmed that Atomos decided "Native" = Vlog. After you said it, I googled it and found the AtomOS release notes update PDF that you're quoting from. This certainly reduces a lot of uncertainty. It's a shame the Atomos rep was not able to clarify this when I emailed them a while ago. The Vlog curve spec defines 8 stops above middle grey, so the max linear value is 46.0855. (0.18*2*2*2*2*2*2*2*2). The fp sensor clips way before the max value that Vlog was designed to hold so it should not be an issue. Based on the test clip you recently uploaded with the sun clipping out of the window, it's clipping at about 0.833 in Vlog so that would be like 83 IRE. In scene reflectance terms once converted from Vlog to linear in Nuke, that's 9.36. So it's clipping more than 2 stops below the Vlog max value. This screengrab illustrates where that is in relation to the entire scene reflectance range defined by the Vlog curve. Specifically this shows a Vlog to linear transform, so it's the inverse of a Vlog curve. At the bottom, the input numbers represent the equivalent of an "IRE value" (0.83) and the output numbers represent the scene linear value (about 9.4, matches Nuke). So as you can see, there's a ton of headroom remaining that will never get used. 7 hours ago, OleB said: As far as I understand from the Vlog white paper 90% reflection is located at about 60 IRE, on ISO 100 the fp clips at about 62 IRE. The higher you go with the ISO (up to ISO 800). The more headroom on top is available. That means on the same Vlog to linear transform the input is about 0.59 and the output is 0.9. Here's a screengrab showing you how much extra headroom you get for capturing highlights above that. You basically get all of the curve to the right of the green arrow I drew. So while it's not ideal that Sigma don't have their own log curve, Vlog is okay as a monitoring option on the Ninja V. 8 hours ago, OleB said: However I am not too sure if this is at least for me a good way of working since I do not know if the next step would be now to figure out the native ISO of the camera for maximum DR in Vlog? It doesn't matter what ISO you use, you will never use up all of Vlog. This is assuming there's no funny business going on where the Atomos is somehow clipping the highlights as they come in from the camera, but I doubt that. 8 hours ago, OleB said: For now I prefer the manual colorspace matching in FCPX directly from the untouched linear RAW, which gives me great results. And with the PQ view in the monitor I can get a really good idea on how the picture will look like. Just to clarify, it doesn't matter which monitoring option you choose on the Ninja V, the underlying file is exactly the same. The difference between monitoring in PQ or V-log is that Vlog requires you add your own LUT, while PQ out of box creates a "display" image that takes advantage of the extra nits of the Ninja V but it's just a consumer HDR display standard for TVs. So if you want to view the same image while shooting as in your timeline, you would match the display settings in both the Ninja V and FCPX, which is all you do in any software/hardware combo anyway. All that's been figured out is that the "Native" input is a known log format (Vlog), so that means it's easy to figure out how to load the look from your editing/grading software into the Ninja V. OleB and Noli 1 1 Quote Link to comment Share on other sites More sharing options...
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