F35: Alexa lut for the F35?

macgregor

macgregor

Veteran
You might need to make Slog flatter but if you want to give it a try here you go.
This version of the alexa lut doesn't have the gamut correction. This is good, because sony's and arri's primaries aren't the same, so if you apply the regular davinci resolve alexa lut to the sony footage, colors will go crazy. If I had access to an alexa for a couple hours I could even create a lut to tranform the F35 Slog to Arri's Clog values. That'd be super sweet, no more guessing.

http://www.arri.com:80/fileadmin/ad...=1&shoulder=1&3d=3d&dim=&bits=&format=davinci
 
I have an alexa and an f35 and an xrite colour checker.. I was planning on doing some tests soon. But I've shot with two f35's in the past and the colours/white balance were a bit off from each other. both cine-e mode. but didn't have time to investigate further... So i'm not sure how universal these luts will be??

I could post some clips when I'm done in a week. Any advice on resetting the sony and what setting to use?
 
Looks nice and natural Miguel. I built an F35 LC709A LUT for Resolve (LC709A being Sonys approximation of the Alexa's Rec709 look), which seemed to serve a similar purpose quite nicely. And simply having to do gamma transforms from SLOG to SLOG3 certainly simplifies things.
 
Yeah exactly, the WB will be off and color gamut different. It'd be great if we could get a few shots to see how they can match.
Could you email me?
 
macgregor said:
You might need to make Slog flatter but if you want to give it a try here you go.
This version of the alexa lut doesn't have the gamut correction. This is good, because sony's and arri's primaries aren't the same, so if you apply the regular davinci resolve alexa lut to the sony footage, colors will go crazy. If I had access to an alexa for a couple hours I could even create a lut to tranform the F35 Slog to Arri's Clog values. That'd be super sweet, no more guessing.

http://www.arri.com:80/fileadmin/ad...=1&shoulder=1&3d=3d&dim=&bits=&format=davinci
Click to expand...
This may be a stupid question but why would anyone not start a proper grading process in Resolve with using a correct input colorspace transformation of the Sony log curve instead of using a LUT from another camera manufacturer?
 
Well, one thing is color space, the other is log values. I'm not a super expert here on any of the two. Main issue is finding a good colorspace transformation. I don't like the Sony S-gamut ones that come with Resolve.
I do like however the way the Alexa lut handles the highlights. However you cannot simply apply the alexa lut to any other camera because it also contains colorspace transformation. That´s why using the log to video lut (without colorspace transormation) could be useful.
 
Hi macgregor, just my 2c here!

Did you try to create an S-Log/S-Gamut to LogC (Sup 3.x, ...)/Alexa Wide Gamut LUT in LUTCalc and use Resolves Alexa 709 LUT? That usually works nicely for me. A 1D LUT might be fine, but the Alexa LUT does the "less saturation thing" to the highlights, which you don't get with a 1D LUT.
In your YT video I saw that you used the F900R color space, which I'm not that familiar with. This is more of a 709 color space right? In that case you might need to switch to S-Log/709 in LUTCalc.

Let me know if and how it worked for you!

BR
Michael
 
I've enjoyed this thread and hope it continues.

Has anyone tried the Koji Color film emulsion LUTs developed by Dale Grahn, color timer for Gladiator, Private Ryan and the like on F35? For that matter does anyone have an experienced opinion with these LUTs?
 
Here you go boiz!

F35 Link - http://bit.ly/2lC0LxX
Alexa Link - http://bit.ly/2lBSTNd

Alexa PLUS 16:9 was set to 1080p 4444 Internal - Log Log
F35 was set to 1080p 12bit 4444 Odyssey 7Q - Slog Slog Cine-EI


I shot from the white point clipping to as low as I could go with every stop in between. And a lens capped shot in there at the end. Only had time to do a tungsten test though. It's way too hot under a redhead :)

There's a mixed lighting comparison as well. With the worst CFL I've ever found. Because the main difference I've found with matching cameras is how they see mixed light. There's always a sneaky LED or Fluro messing up everything I do :/

WARNING - I've shot with two F35's before and the colours were a little off from each other. So I'm not sure how consistent any LUTs made from this will be...

Next time I'll try out F900 Colour Space. I completely forgot about it while doing this.

Have fun!!!
 
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Just looked at the footage properly.. there's a weird milky haze over the left hand side of the Alexa footage... must have smudged the lens.. Sorry guys.
 
Wowowo this is great news, at least for me.
Even though those tests you uploaded weren't perfect, I was able to remap the F35 Slog into Alexa values and then apply the 1D Alexa lut from the Arri site and after combining both I was able to create a grade/lut that improves my original Slog to 709 by a subtle but amazing margin.
I will be using this from now on. It might not be perfect yet but it's so much better with highlights than the old one.
https://www.dropbox.com/s/nsg60q81ib6brqo/F35 sgamut with Alexa lut to 709.cube?dl=0


Patrick, if you had a chance of shooting a couple exterior shots with high contrast on the F35 in 422, 444 and Alexa 1080p 422 and 444 also that'd be super sweet, that way I can test if this new grade a bit more. And keep the framing locked! ;D
 
Dang you guys are like- classic digital cine cam mad scientists. Thanks for the efforts cleaning up what usually becomes a contrived effort to grade Slog1. Looking forward to toggling this new .cube on the odyssey. Mac do you still recommend using the F900 colorspace?
 
I'm not sure about the F900R/900 color space vs Sgamut. I'd need to make more tests.
I see no downsides with F900R/900 colorspace though.

but holy crap, this new lut makes things so much better. I'm just re-applying it to footage I shot years ago and it's making me happy.

BTW, davinci resolve seems to have fixed the prores444 data levels issue. It seems we get the full range now. Can anyone confirm this too?
 
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macgregor said:
Wowowo this is great news, at least for me.
Even though those tests you uploaded weren't perfect, I was able to remap the F35 Slog into Alexa values and then apply the 1D Alexa lut from the Arri site and after combining both I was able to create a grade/lut that improves my original Slog to 709 by a subtle but amazing margin.
I will be using this from now on. It might not be perfect yet but it's so much better with highlights than the old one.
https://www.dropbox.com/s/nsg60q81ib6brqo/F35 sgamut with Alexa lut to 709.cube?dl=0


Patrick, if you had a chance of shooting a couple exterior shots with high contrast on the F35 in 422, 444 and Alexa 1080p 422 and 444 also that'd be super sweet, that way I can test if this new grade a bit more. And keep the framing locked! ;D
Click to expand...

Nice mac! But just a question. This lut is to convert slog to arri clog right? This is what I understood. But I ask because you named the lut sgamut to alexa instead of slog to alexa. But it has nothing to do with color right? Is the name a typo?

So you use this lut in first node in resolve and then the arri to rec709 lut from arri's site in last node after all the grading?
 
trafficn said:
Dang you guys are like- classic digital cine cam mad scientists. Thanks for the efforts cleaning up what usually becomes a contrived effort to grade Slog1. Looking forward to toggling this new .cube on the odyssey. Mac do you still recommend using the F900 colorspace?
Click to expand...

Yes it is great mac still on board and keeping the ball rolling. So may have come and gone. But F35 is stil best. I wonder how many here still have F35. I think from originals of couple of years ago is only me and maybe 1 or 2 more. I see some new people who look to have F35 but not sure how many. I think F65 is now only 1 since I think JMDP finally got rid of his.

Thanks for keeping ball rolling mac!
 
Yep 12.5.3 didn't have full data levels on 444 but 12.5.5 now does!! :)

Also my tripod is currently being serviced so I'll try to get out there and shoot some more once it's back!

That new LUT is pretty sexy Mac :)

I know this is all in the interest of accuracy. But if you're keen, you should try out my colour pallet modifier LUT.
It's basically a 30% 5207 colour only LUT tweaked for the F35. Designed to go before your 709 LUT.

Slog colours always seem to be yellow/green biased. Which might be more accurate? But I do like the softer magenta bias of the Alexa for skin tones and unbalanced light. And this is my current solution to push the F35 to more Alexa like colours.

Link - http://bit.ly/2msWmSb


Side question - Is this what F900 colour does??? I'm still yet to test it out..
 
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