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I have some Magic Lantern Raw footage that I want to convert to Prores 444 for use in this workflowenter link description here.

I understand the process, other than the use of LUTs.

In the process, an application called MLRawViewer is used to convert .mlv files to ProRes444 files. In this conversions process, a LUT is selected. My confusion lies in the selection of the LUT.

I want the ProRes file to be as flexible as possible for grading later in the process, and I have no desire to use a LUT to give the footage a particular look.

So which LUT should I choose? What should inform this decision?

  • What choices are available? – Jason Conrad Jan 10 '15 at 16:04
  • @JasonConrad The options are: Log-C, C-Log, Linear, HDR global tone map, Log 8, sRGB, Rec.709, S-Log2 – Undistraction Jan 10 '15 at 17:29
  • sRGB and Rec.709 are saturated and contrasty. They're for final delivery (709 being the broadcast standard for TV, and srgb for computer monitors). You'd only use those if you liked the way they looked and decided that you didn't want to do any further adjustment. As for the rest, I use S-Log2 a lot, and am pretty comfortable with it, both with our Sony cameras, and Blackmagic. I've used C-Log a little, and it's similar, so it's probably OK, but I haven't graded any ML RAW, so that could be a totally different beast. As I say below, trial and error, my friend. – Jason Conrad Jan 11 '15 at 11:32
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I'd pick something that looks flat and unsaturated. Those are usually the ones designed to retain detail. If you see clog or slog2, those are good. Rec 709 will throw out info, so don't use that.

What should inform this decision?

Trial and error. A lut is really just a starting point for your grade. Try some different ones out. If it absolutely butchers the color, then it's probably not a good place to start. If you see clipping or banding, then you've chosen a lut which was meant for a different situation. As you try each one, look at the trace on a waveform monitor and vector scope. If anything goes out of bounds, pick something else. Do you notice any kind of granularity, banding, or stair-stepping in the traces? Look for one that's more even.

  • Thanks for replying. You say 'A lut is really just a starting point for your grade', but in this situation, where I am discarding all of the sensor data, why would I want to do anything other than retain the maximum possible amount of data? Why might I want to do something else? – Undistraction Jan 10 '15 at 17:27
  • It depends on how you plan to work with the footage. From your question, I assumed (perhaps incorrectly) that you plan to throw away the RAW, keep a lut-ed version of the prores, and edit and grade from that. To answer your question, "why might I want to do something else": You might save the RAW, and export rec 709 proxies to an editor (rec 709 because it's ok to look at, not good to grade. Editors don't like staring at log all day. proxy b/c it edits quickly). He returns the timing of his edits to you. You do your colorist work on the original RAW, no quality sacrifice, effort minimal – Jason Conrad Jan 11 '15 at 11:12
  • If that doesn't make sense, I'll add it to my answer and do a longer writeup. I was just trying to fit an explanation of "round tripping" into 600 characters. – Jason Conrad Jan 11 '15 at 11:19
  • Thank you very much. That has really helped clear things up in my head. If you have time, an expanded answer would be great for me and for anyone coming to this question fresh. – Undistraction Jan 11 '15 at 11:42

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