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Grading 5D Mark IV C-log

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Markus Stone
Grading 5D Mark IV C-log
on Sep 20, 2017 at 7:04:42 am

I feel like I'm missing something here. I've never really worked with alternative colour spaces before or played much with LUTs, but now I've gone and upgraded my Mark iv to C-Log, I figure there should be a standard LUT that you can throw into Lumetri as a starting point for further manipulation - something that converts C-Log to something that looks more like Rec709. Maybe I have the workflow all backwards here. Is there a standard 5D Mark iv C-Log LUT for editors? Canon don't seem to know anything about it and I can't find it in Premiere. The LUTs Canon mention of are internal to the camera for monitoring in live view and via the HDMI cable. AFAIK, there's nothing you can download for use in Premiere.

Help!

Markus


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Chris Wright
Re: Grading 5D Mark IV C-log
on Sep 20, 2017 at 7:53:53 am
Last Edited By Chris Wright on Sep 20, 2017 at 9:36:38 am

abel converted the canon luts so they're compatible with premiere by remarking the #size line lut in notepad
https://abelcinesalesforce2.s3.amazonaws.com/article/canon-luts-for-the-c10...

keep in mind canon, abel, iwltap all have them as 32 cube. I grade heavily so I don't go below 64 cube. I'm not aware of any 64 cube readily available. most websites actually only sell at 32. If you want, I could make a free 64 lut . I would need a good close up of skin for skin tone line and a good dynamic range. it would also have to be white balanced and low iso to work correctly. technically all 3d luts don't know what iso your camera is at so there's always a 10% gap between reality and digital. but perfect white balance is critical or the lut is useless for one click go.


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Markus Stone
Re: Grading 5D Mark IV C-log
on Sep 20, 2017 at 11:05:13 am

Wow, thanks for the info!

I'd love to take you up on your offer, but I'm not sure I could pull off the test conditions you need.

My understanding is that ISO 400 yields the greatest dynamic range in C-log mode on the 5D's. Is that low enough?

Then if I expose caucasian skin to 70 IRE in soft even light that should give you what you need?

Anyway I'm still struggling to understand which input LUT relates to my footage from the 5D. At the moment I'm playing with BT709_CanonLog_BT_to_WideDR_65_FF_Ver1.1 which as far as I can tell from the documentation and my tests looks best


Best,

Markus


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Markus Stone
Re: Grading 5D Mark IV C-log
on Sep 26, 2017 at 3:11:45 am

Yep, I'm not sure this C-Log thing is working for me.

As we all know, C-Log footage is kind of grey. The best LUT I've found so far is "Canon Log 10 to Wide DR FF" but even that still leaves the footage kind of greyish

When I grade to get dense blacks, sure the highlights are a stop or two better, but it makes everything else unacceptably noisy and throws a yellowish cast over everything that is hard to get rid of (probably due to my inexperience).

Once graded, it seems to be that you rescue the highlights at the cost of the skin tones which makes it useless. I find HDR mode gives far better results.

I've heard that you should overexpose a little to prevent noise in the final image. Okay. But then you lose the highlights and again, this destroys the whole point of C-Log, doesn't it?

Any ideas what I might be doing wrong here, or is it all overhyped (or should I be recording RAW to an external device to take advantage of it?).

Best

Markus


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Chris Wright
Re: Grading 5D Mark IV C-log
on Sep 26, 2017 at 8:54:01 am

this quick tut shows how to make your own lut in lumetri. then just open lumetri color in view and click the dashes to export a cube. note, this doesn't support fast color corrector's hue control so use lumetri's temp controls instead.

-how to grade flat video in 60 seconds in premiere.
https://forums.creativecow.net/readpost/394/232

---or

the only downside to lumetri is that you can't change the hue. you can actually make your own free lut inside photoshop.

grade inside photoshop convert video to smart object or just export one png frame, and go to filter-camera raw filter, then save preset as .xmp. then
download
https://sellfy.com/p/aQ1y/
after generating its lut table, take that png into photoshop, apply your .xmp preset in adobe camera raw and save-as a new filename.
then open iwltap lut creator(click its question box to select 64 cube) and select the new filename. it will create a brand new 64 cube lut.
-
if you post an example image I can show you what I mean. you can make your own luts align perfectly with the the skin tone line, 3d rotate your colors, and even adjust the camera raw sensor data(rightmost button) so that you can get normally impossible colors that would normally clip or over saturate in lumetri and still look awesome.


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