There is a great blog post on Abelcine about applying LUTs to log footage in various applications. Since I’m shooting S-LOG2 on Sony FS700 and in Film mode on Blackmagic Design Pocket Camera I deal with a lot of log footage. My NLE of choice is Final Cut Pro X and there is a problem with mentioned process in the blog post. The blog states using a plugin LUT Utility for applying LUTs to log footage. You apply the plugin as any other plugin and it appears in the effects tab.
Here is where the problem starts.
The app first applies all the effects before it applies Color Grade under Color. When you apply LUT you are applying effect that most of the time crushes the blacks and/or highlights. That means that it can only be applied to the perfectly shot footage. But we all know that is easier said than done. Log footage looks very flat and is as such difficult to determine correct exposure. The best way would be if you could set exposure on a monitor with LUT applied (like Odyssey 7Q) or use a light meter like Lumu (I’m having one on test at the moment and will write a review soon). But sometimes you don’t have the time or you just have to shoot as light as possible and you have to judge the exposure with the help of build in histograms or zebras.
This shot was shot underexposed to protect the highlights of the molten metal. It was shot on Blackmagic Pocket Cinema Camera w/ SLR Magic Anamorphot 1.33 X – 50 lens and SLR Magic CINE II 35mm T1.4 taking lens in raw mode. It was than converted to ProRes in Resolve with protect highlights option enabled. Footage was than imported to Final Cut Pro X. When you apply the LUT it crushes the blacks (cause the shot was underexposed). So you should lift the blacks and mids a bit and than apply the LUT effect. But this is not possible because FCPX first applies effects tab and only than Color tab and those two tabs or effects in the tabs are not able to concatenate. Nick Shaw kindly corrected me on twitter that it is not concatenation but order of operations.
Crushed blacks. You can lift them but you would only be lifting the low part of histogram as it is and would not be getting any more information in the blacks.
But there is another way by using the Adjustment layer. This is the trick I learned from great Steve Martin & Mark Spencer at Ripple Training. You can download the RT Adjustment Layer Title from the Ripple Training site and learn there how to install and use it. The thing is now FCPX first applies the Color tab to the clip and only than the Effects that are on the Adjustment layer. So you can lift the blacks and/or lower the highlights before applying the LUT. This option has it quirks (mostly regarding the rendering), but is in my opinion the best method for working with log material in Final Cut Pro X.
You can see that the blacks are no longer crushed and you have lots of details in them.
As of version 10.1.2 of Final Cut Pro X you have an option to apply (in the Metadata settings view) a broadcast standard Rec.709 look up table to footage captured in log to cameras from ARRI, Blackmagic Design, Canon, and Sony. This works with high-dynamic-range and wide-colour-gamut footage in real time, but is the same as before when you applied the LUT directly to clip. You get crushed blacks and highlights on not perfectly shot footage and you can’t correct it afterwards in Color tab.