How to adapt any LUT for the Alexa 35

Рет қаралды 8,073

5 ай бұрын

ARRI quietly updated their Alexa 35, letting us install custom LUTs into the camera. But they need to be in the right format, check out the video to see how to make ’em right.
You can grab the ARRI Reference Tool mentioned in the video here:
www.arri.com/en/learn-help/le...
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Пікірлер: 42

@galaka22 5 ай бұрын

I know you’re not doing grade school this week. Sincerely, thanks for giving us some new information to keep us going.

@equisetuminc 5 ай бұрын

thank you and congratulations on your growing family. 🎉

@artmicca 5 ай бұрын

Thanks for the usable information! 🤝

@honzalouma9583 Ай бұрын

Thank you very much for this super-useful video! Helped ma a lot on set! 👍🏻

@joraphpictures 5 ай бұрын

Thanks you

@MCNoise 5 ай бұрын

I hope they do the same update for the Canon C70

@JonPais 4 ай бұрын

“The reality is that working with images in anything but HDR represents a needless compromise.” - Cullen Kelly, 2020

@CullenKelly 3 ай бұрын

100%

@he.smile_ 5 ай бұрын

9:43 Hi! I think they require the HDR equivalent because the Alexa 35 eyepiece is HDR if I’m not mistaken!

@thatcherfreeman 5 ай бұрын

I could be wrong, but playing with the Alexa 35 simulator, I think you can choose whether you want the evf to monitor the SDR or the HDR image

@movietrailer4113 3 ай бұрын

Cullen is a great solution. Show me how to convert the material to Z-Cam 2 correctly. I came across raw material a long time ago and used the SLOG method of trial. The fact is that there is no direct conversion in DaVinci indicating the conversion of this camera. Is the color solution right to reveal the exact color transfer in the SLOG?

@zenithrebel 5 ай бұрын

Hey quick question, now more and more smartphones can record in log format. I know of the addition of the Apple.log in davinci colour space, but any idea how can i check what log format im in so that i can CST into a rec 709? Im working with my Oneplus11 film log mode and im so confused

@GeraColorz 5 ай бұрын

Hey Cullen, thank you for all the wonderful tips always! Got a question that is happening a lot to me lately. It seems to me DoP's at least where I live have the tendency to create the look in camera, which is not by it's own a bad thing at all, except that it includes exposure as well and the image always appears in the parade from 50 to below in log, which for me in most cases looks under exposed. The thing is as I mostly do commercial work directors/clients always find the image dark and I got to balance it up, which creates a lot of grain and artifacts, destroys the depth of the image, etc. I try explaining it to DoP's but it's always a pain in the ass and they don't seem to be willing to do it as it scares them to ''overexpose'' an image. They shoot RAW almost always which is great but they think that by doing that they will have the latitude to change exposure, which you do but and underexposed image will always bring up artifacts. My petition is, would you consider doing a video which talks about the perfect exposure, contrast ratios, workflows from DoP to colorist so that the image comes as clean as possible? Thank you!

@camilitoo 5 ай бұрын

Hi Cullen! I checked Alexa 35's AWG4 primaries triangle and its vertices doesn't align with the AWG3 color space triangle. Is that something that could become an issue or we don't have to worry about it? Thank you for creating such an amazing content.

@CullenKelly 5 ай бұрын

Great question! No issue there: the difference between those color spaces is accounted for in the CST from AWG4 to AWG3.

@AronBagel 5 ай бұрын

Hey Cullen, does this same principle apply to your DWG LUTs? For example, I’d love to have a custom 2383 conversion LUT based on your DWG 2383 creative LUT.

@CullenKelly 4 ай бұрын

Hey Aron! It absolutely does apply!

@MehmetKozal 5 ай бұрын

I am missing that analog tune in the background

@user-vu6vt7tz6r 5 ай бұрын

Can you convert a Alexa 35 65LUT into a 33 lut? And would I need to make a CST to make those changes from clog4 into clog3?

@CullenKelly 5 ай бұрын

Yep, you can resize a LUT from a 65 pt cube to something like a 33pt cube. Good question! You would also need to apply a conversion in your pipeline if you're planning to use a LogC4 LUT on LogC3 material.

@user-vu6vt7tz6r 5 ай бұрын

Nice would that be the same standard input CST on the timeline node when creating or would I need to make that an entire in-out pipeline? In cst -> arri wide gamma 4 --> in logc4 -->out wide gamma 3--> arri log c3 ? Do I need to add an cst for the output?

@Evitagen1903 4 ай бұрын

⁠@@user-vu6vt7tz6rhey did you find how to make the conversation?

@robinwebster3690 4 ай бұрын

This method works technically, but it does not make use of the full dynamic range of the new camera as you are effectively squishing the logc4 color space into the logc3 color space. This has been covered by Arri in a video on their channel. The only way to convert the LUTs from Logc3 to Logc4 is by eye. This method will make a still image match, tehcnically, but if you tried to import the LUT into the camera, it will not make proper use of the full dynamic range

@CullenKelly 4 ай бұрын

I know Arri has made this argument, but it’s an oversimplified one at best. Utilizing dynamic range isn’t a binary technical proposition, and there’s no wrong way to do it - except one that the image author doesn’t like ;)

@robinwebster3690 4 ай бұрын

@@CullenKelly All i know from real world testing is that this method will produce a normalised image, but does not work effectively over the range of exposures. Unfortunately.

@CullenKelly 4 ай бұрын

@@robinwebster3690 Was this testing done with the latest SUP using the new alf4c format?

@noonitubes8457 4 ай бұрын

@@robinwebster3690can you go a little more in depth as to how it doesn’t work across exposures? I came across the video because I’ve resisted the Alexa 35 simply because all my looks can’t be easily translated. After testing the method in this video at Arri Rental, I was getting what to me looks like accurate results. Toggling between Arri’s built in looks for LogC4, and my own custom look, translated through the video’s steps, there were no wildly differing levels of exposure

@robinwebster3690 4 ай бұрын

@@noonitubes8457 I converted a logc3 LUT to log c4 using a very similar method to CK. Then put an Alexa mini and Alexa 35 with the correct LUT side by side. And a one stop increase on both cameras did not yield the same results. Each LUT is designed for a specific gamma curve with different tonal range. So just by looking at a single example of the converted LUT, it may appear to be exactly the same, but the exposure response across each gamma curve is not the same. You could possibly recreate this test on da Vinci using offset to move the exposure.

@leeksumners 5 ай бұрын

Correct me if I'm wrong, but this workflow basically nerfs the A35. You're converting LogC4/AWG4 to LogC3/AWG3, thereby defeating the purpose of using a A35 and Arri's new Reveal color science. If you're using these LUTs on an A35 for exposure on set, everything will be about a stop and half over-exposed.

@CullenKelly 5 ай бұрын

Thanks for bringing this up! Happy to say that’s not the case - you can see in the video that exposure is being appropriately compensated when using this workflow. The scenario where you’d get the results you’re describing would be if you skipped the LUT adaptation process I showed in Resolve altogether.

@leeksumners 5 ай бұрын

@@CullenKelly Not true. The stuff in your timeline was already properly exposed. When you put on your old trusty 709 LUT onto the LogC4 footage before the conversion, it was a stop and half underexposed. Then you did the conversion from LogC4 to LogC3 and it looked correct. If you do this LogC4 to LogC3 conversion, then load that LUT into the A35 and and exposed for the LogC3 LUT, it will be a stop and half over exposed. The A35 has 3 extra stops of latitude, and it's mainly in the highlights. The old Arri stuff is 14 stops. You can't use the same LUTs you've used for years to expose...if you do use the old LUTs, you might as well just shoot on the MiniLF or Mini because you're nerfing the camera.

@CullenKelly 5 ай бұрын

@@leeksumnersI see how you’re getting there, but the conclusion isn’t quite right. Happy to do a full breakdown in next session of Grade School!

@jackeylee416 5 ай бұрын

@@CullenKellyHi Cullen, thank you for your time and effort to cover this topic. I’m curious as well if your process will nerf the capabilities of the Alexa 35. I just watched a video from kzfaq.info/get/bejne/btVhdpaVzqfRnok.htmlsi=J6ER8I4iVH9rcely It’s a senior colorist at Arri explaining how you could recreate Alexa Look File 2 into 4 without compromising the ability of the camera. I was wondering what’s the difference between both of your methods and if your method could apply to not only LUTS but Look Files as well.

@robinwebster3690 4 ай бұрын

@@CullenKelly He is correct, there is an Arri video about this on their channel. I can also confirm, from personal experience that this method will create a technical match inside Resolve, but not the results you expect when the LUT is used in the camera.