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R
Rombau
Participating Frequently
June 20, 2024
Question

Problèmes d'apparence de plans tournés en S-Log3

  • June 20, 2024
  • 2 replies
  • 545 views

Bonjour,

j'ai un projet avec des rushes tournés avec un FX3 et un FX6. Tous les plans ont été tournés en S-Log3.

J'ai monté pendant un certain temps en mixant ces deux sources et il n'y avait aucun souci.

 

Sauf qu'un jour, en redémarrant Première, j'ai constaté que les plans provenant de la FX6 avaient comme une LUT intégrée (avec plus de sat et de contraste) et qu'ils n'avaient plus du tout l'apparence Flat du S-Log3. Ce qui a créé une grosse différence avec les plans de la FX3, qui eux n'ont pas subi ce problème. J'ai même dû supprimer l'étalo provisoire que j'avais moi-même appliqué.

 

J'ai bien vérifié et aucune LUT d'entrée n'est appliquée dans lumetri, ni aucun look dans l'onglet créatif.

J'ai déjà travaillé plusieurs fois avec cette configuration de tournage et je n'ai jamais eu de problème. J'ai l'impression que c'est depuis que j'ai téléchargé l'application Catalyst Browse.

Savez-vous si l'application Sony peut avoir une influence sur les rushes importés en Première ? Je précise que les plans de la FX3 mais aussi ceux de la FX6 ont bien l'aspect Flat du S-Log3 dans Catalyst Browse.

 

Que puis-je faire pour restaurer l'apparence des rushes S-Log3 de la FX6 dans Première Pro s'il vous plaît ?

 

Merci pour votre attention.

This topic has been closed for replies.

2 replies

R Neil Haugen
R Neil Haugen
Legend
July 1, 2024

I work for/with/teach pro colorists, have for some time. So a few comments ...

 

All of the program color management and image color management options are now in one place, the Lumetri Panel's Settings Tab ... the one named Settings. That's where you check and set things.

 

It sounds like auto detect log and auto tonemapping are both 'on' in your color management in Premiere. That would do this, but it is using an algorithmic tonemapping, NOT a LUT for the normalization to Rec.709.

 

So deselecting those two options should get you a log-appearing image for any log-encoded media.

 

Algorithmic transforms are generally vastly better and safer as a means of normalization, by the way. LUTs can be incredibly useful, but if not used carefully, incredibly destructive. Algo transforms simply can't mangle data like a LUT might be able to.

 

And there is no "perfect" correct for all situations log to Rec.709 LUT made. All transform LUTs must be built with assumptions for scene/exposure brightness, contrast, and saturation ranges plus naturally all are then modified to some "pleasing" appearence ... there is always an aesthetic component within any normalization process. 

 

Which aesthetic choice do you like with this media from this scene? That is always a colorist's question.

 

Next, Premiere's auto-detect log function works with most variants of S-log3 ... but there is one 'variant' of Sony S-log3 that actually does not have log encoded data in the file. It's actually a "log-like" setting of the camera settings for contrast and saturation. And that variant, as it isn't actually log data, does not get 'recognized' and normalized to screen/linear data in Premiere.

 

So I wonder if that may be the situation here ... possibly.

Everyone's mileage always varies ...
R
RombauAuthor
Participating Frequently
July 2, 2024

Thanks a lot for your answer.

 

Unfortunately, I'm not an expert in colorimetry so it all seems quite complex to me.

 

Can tell me how turn off the auto-tonemapping option and turn off auto detect log please ?

R Neil Haugen
R Neil Haugen
Legend
July 2, 2024

That's right up top in my reply ... ALL color management settings are in the Lumetri panel settings tab.

 

Although it's more work to turn that off, you're welcome to do so. As my guess is the FX3 footage is not actually log encoded, that the chosen setting just uses super-flat settings in camera to look like log ... which that camera can do in one of the built-in options.

 

So my normal process would be to use the superior algorithmic transform for the FX6 over a LUT process, and simply create a Lumetri preset to expand contrast/sat for the FX3 to a similar state. Select the FX3 clips in the bin, drag/drop the preset on them.

 

Done with normalization.

Everyone's mileage always varies ...
Mike Dziennik
Community Expert
Mike DziennikCommunity Expert
Community Expert
July 1, 2024

There's likely a mismatch somewhere.

With a clip on the sequence selected and the Lumetri panel open, have you checked the 3x places adjustments can be applied? With the "Edit" tabe selected, you can adjust both the source and sequence colour adjustments. Then with the "Settings" tab selected you can set the source clips Colorspace and Input Lut. Check these 3 locations on both your FX3 & FX6 to see where the mismatch is.

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