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-   -   J-LOG and LUTs (https://www.dvinfo.net/forum/jvc-4kcam-pro-handheld-camcorders/529923-j-log-luts.html)

Dave Bittner October 2nd, 2015 01:02 PM

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.

Thanks!

Steve Rosen October 2nd, 2015 04:34 PM

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.

Lee Powell October 19th, 2015 02:56 PM

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.

Alex Humphrey November 28th, 2016 12:00 PM

Re: J-LOG and LUTs
 
If you haven't looked at JVC's support side, here is a link for their suggested dealing with J Log on FCPX platform. http://pro.jvc.com/pro/attributes/4k...CP_D-LUT-3.pdf

I'm learning to use it myself. JVC's paper says before applying LUT to go into FCPX's Color, select Exposure and adjust highlights to BELOW 700mV. (usually -8%) Then apply the LUT cube in FCP (i'm using Color Finale to import LUT cubes as well as do some color correction, though there are many software plug ins to choose from.. I think the latest FCPX now has LUX importing as well.

Noa Put November 28th, 2016 12:06 PM

Re: J-LOG and LUTs
 
I"m using leeming lut (Leeming LUT One) which is easy to apply in edius 8wg as their 8.22 update added lut support for the ls300.

William Hohauser November 28th, 2016 02:25 PM

Re: J-LOG and LUTs
 
Quote:

Originally Posted by Alex Humphrey (Post 1924119)
If you haven't looked at JVC's support side, here is a link for their suggested dealing with J Log on FCPX platform. http://pro.jvc.com/pro/attributes/4k...CP_D-LUT-3.pdf

I'm learning to use it myself. JVC's paper says before applying LUT to go into FCPX's Color, select Exposure and adjust highlights to BELOW 700mV. (usually -8%) Then apply the LUT cube in FCP (i'm using Color Finale to import LUT cubes as well as do some color correction, though there are many software plug ins to choose from.. I think the latest FCPX now has LUX importing as well.

Do you get a Color Finale error message using the JVC Tungsten LUT in Color Finale yet it still works? I get that every now and then when I launch a project with the LUT applied.

Alex Humphrey November 29th, 2016 09:19 PM

Re: J-LOG and LUTs
 
1 Attachment(s)
Haven't seem to, but I've applied mostly the JVC daylight LUT in FCPX. though it was buggy and crashed once or twice I think due to HDD speed.

Also I had a major improvement when I read the instructions about using 18% grey cards. Grey card should read about 36% for proper Log exposure, not the typical 45-50% for normal metering. I did that and simply applied the Lut and got this, though can't guarantee I had 36% since I was chasing the cat around with a 80-200 f4 Nikon lens on the JVC. Looks pretty good, but some 8 bit compression, most of which is from photoshop, but it is still there. Between Adobe Photoshop and this webpage the image came out quite a bit darker.

Duncan Craig November 30th, 2016 02:13 AM

Re: J-LOG and LUTs
 
I'm using m-LUT in FCPX and it's been behaving quite well.
I'm still using a late version of 10.2 and an older OS.

Here's a recent job:

Regarding exposure, I definitely push the histogram right (checking that peak whites aren't over 800% if I want to keep them), it's as if you can see the midtones becoming too crushed or compressed when you over expose too much. After reading so much about Log shooting exposure techniques, using J-Log seems really easy to me.

I've got another edit going online soon which I'm quite proud of (a rarity) so I'll post that when I can.

Alex Humphrey December 1st, 2016 12:01 PM

Re: J-LOG and LUTs
 
I'm getting some better results since my last post in shooting with spot meter using the Zone system that I learned from college photography days.... 18% grey card reading 18% in the viewfinder. My face reading about 25-30% with the spot meter (the fill exposure not edge highlight of face). Bringing into FCPX with the Color Finale plug in and applying the JVC cube LUT. and it's pretty good. (brighter than my cat above) The other LUTS that came with Color Finale seem more usable now. I got other good results by NOT applying the LUT, and doing a milder S curve and adjusting gama/color in the Color Finale plug in.

I will do more experimentation this month and if anyone is interested I'll post my results. To confuse the issue one of my grey cards (not 18%) but my digital Neutral grey card isn't 18% grey but much lighter. 2 stops lighter? Everyone seems to be using these lighter grey cards for color correction and I'm guessing not for exposure..

Here is Steve Mullen's article on exposure for the JVC LS300 if anyone hasn't read it.

https://www.thebroadcastbridge.com/c...h-j-log-part-2

Alex Humphrey December 6th, 2016 10:48 AM

Re: J-LOG and LUTs
 
1 Attachment(s)
I am liking Color Finale Pro plug in for FCPX. Now that I think I know how to shoot J-LOG here is my first 10 minutes with Color Finale Pro. I don't know if I did this in the correct order, but it made sense to me last night. Never having used LOG in any camera or any deep color correcting except in college with B&W and color reversal film and some color CibaChrome printing, this is my shot in the dark.

1. Shot JVC J-LOG with the sky in the spotmeter 300-400% mostly around 350% in my waveform monitor (more accurate) I could se when I was really clipping and when I wasn't so I used that more. In the viewfinder the sky was completely washed out and in my waveform monitor could tell there was sky data, but I relied on the waveform monitor more.

2. Imported into FCPX and used the Color Finale Pro plug in. Enabled Color Management and set input camera Canon EOS. Other options where various generic S Logs. but the Canon gave the first best look at first. I dropped the exposure down to regain the sky detail.

3. Still inside Color Final Pro plug in with the free "BONUS" LUT's and Looks from Color Grading Central (where I purchased the Color Finale Pro plug in) I picked ImpulZ Log Generic - Log LPP Tetrachrome 400 FC.cube and applied it. It gave me deep saturated blue sky and cast the green into a red cast.

4. Still inside Color Finale Pro pluginI went into the "Curves" section and lifted the low to mids slightly to bring up the shadow foreground.

5. Still inside Color Finale Pro plugin I went to Color Wheel. Added a little lift (blacks), Gama (lifted midtones a little) and dropped Gama slightly. Went out of Color Finale Pro plugin back to FCP effects and apply Sharpness 1 just to sharpen a little.

I'm not saying I did this right but I am happy with my first 10 minutes of experimenting with Color Finale Pro now that I know to give J-LOG enough light to work with. My tests earlier this week where terrible. Lots of noise in midtones and shadows. But this worked pretty well.

What plug-ins or other programs is everyone else using?


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