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Old October 2nd, 2015, 01:02 PM   #1
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Join Date: Sep 2008
Location: Columbia, MD USA
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J-LOG and LUTs

I'm a newbie when it comes to working with LOG footage, and I'm hoping to get some clarification of what we should expect from JVC. Will there be LUTs distributed that I can apply to my footage via NLE plugins, and/or will they work with Apple to get the LUT preloaded into FCPX, the way Arri, Black Magic, Canon and Sony have?

Trying to wrap my head around the workflow.

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Old October 2nd, 2015, 04:34 PM   #2
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Re: J-LOG and LUTs

I'm not a colorist, at least I'm not that good at it - that's one of the reasons I like the LS300 after two years, 6 short docs and over a dozen TV spots with Pocket Cams.

I've shot several interiors and an exterior with J-LOG and to be honest, all it really looks like it's doing is opening up the shadows. If I lay a well exposed clip in FCPX, add Color and bring the blacks down about 5-10 points it looks pretty good just like that. The actual skin tones seem to be truer that Cinema Gamma (which requires a little minus green depending on the lens). Give it a try. Shoot a scene in LOG and Cinema and compare them.

Because the blacks aren't deep, it makes focusing with an external EVF slightly more difficult (nothing like the Pocket though) because unfortunately the camera's LUT doesn't export through the SDI/HDMI. I'll probably up the contrast on the Gratical, but right now I'm using it with another camera too.

I forgot to add. I shoot Cinema with saturation set at Cinema Subdued, unlike the example in the clip (one of the three you posted). It's much more pleasing and looks pretty similar to the graded clip at the end of the clip. I'm shooing about three hours tonight, an opening for a doc about an artist - a lot of people expounding about art - and plan to use that setting until I'm more comfortable with LOG.

Last edited by Steve Rosen; October 2nd, 2015 at 04:46 PM. Reason: Forgot
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Old October 19th, 2015, 02:56 PM   #3
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Re: J-LOG and LUTs

J-Log1 footage is recorded with a black level pedestal very close to the 7.5 IRE (8-bit level 16) used in standard Rec. 709 format. With J-Log1, however, highlights extend logarithmically up to 108 IRE, which exceeds the 100 IRE (8-bit level 235) white level of Rec. 709. If you set Zebra Bottom to 90%, you can use it to keep highlights below 100 IRE and your J-Log1 footage will be constrained to the standard Rec. 709 range. Your original footage can then be played back directly over HDMI with correct black and white levels, no LUT required. Shadows will appear brighter in J-Log1 than footage shot in ITU709 or Cinema Gamma.

When J-Log1 footage is loaded into Adobe After Effects, it is interpreted on a full-range scale (8-bit levels 0-255). That makes its 7.5 IRE black level appear gray. This can be corrected by applying a small negative correction to its Master Pedestal setting, which will also lower its 108 IRE white level close to 100 IRE. I find that a good starting point for further color grading.
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