Creating LUTS: The Importance of Exposure

Master colorist David Cole shares the importance of working with exposure tests. Exposure tests help colorists create LUTs as well as assist cinematographers in understanding how to rate the camera and determine what the utmost limits of exposure are before experiencing artifacts, noise, and clipping.

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#colorist #colorcorrection #postproduction #colorcorrecting #lut #lookuptable #exposure #exposuretests #cameratests #filmmaking #filmmaker #cinematography #filmeducation #lutcreation

[BluFinanceTV]

I am not an expert in this field but i learnt something of value from your video (exposure). Thank you for sharing your valuable knowledge.

[peternavanac]

Awesome! Super helpful advice to know ahead of time before you shoot a scene/project

[ArnoldTohtFan]

Is there any way to contact David if we have further questions?

[_ybnn]

Compensate exposure with color space aware tools or linear space in order to get mathematical correct expo comp.

[LeoArmenta]

How can we avoid the noise??? Overexposing in camera or underexposing???? Greethings!!!

[JimRobinson-colors]

Seems to me that using that process, that you would have to know as a colorist the intention of the photography before grading. What if the DP wanted to have a scene one stop over or two stops under? When you make a compensation LUT then the DP would have to have really good communication with the colorist on every clip on every scene. Wouldn't the DP just set to manufacturers middle grey, then light the scene to what they would like. Do you do these compensation LUTs for all your show luts? I would be afraid that the DP would want a 1 stop over look and I would then ruin it.

[jtnfilm]

You would have to be crazy meticulous in pre prod to make this work.

Generally speaking, messing about with over or under exposing digital cameras is not ideal. If you go over or under you're changing the saturation/luminance relationship outside of the intended colour space. The whole ETTR is a left over from 35mm days because the highlight retention was more of a guarantee but people just kind of adopted that for digital thinking it magically gets rid of noise.

Exposure is exposure, there's the intended exposure for most latitude and best colour rendition for each camera then there's everything else.

When shooting, if your shadows are noisy then add light and if your highlights are clipping then ND and fill to taste. In my experience it almost always comes down to adding more light for the cleanest image.

I'd say this video is much more about testing the camera latitude (breaking point) than creating useful LUTs for production.

[kedbear]

Honestly this is surprisingly poor advice and will lead to many problems, for example the approach of using a LUT to compensate for exposure means the LUT won't fit into a color managed workflow, eg if you were using VFX shots, other cameras and so on. If you want to under or over expose the camera, use ISO/ASA instead because it will do exactly the same thing but be far less prone to serious problems in post or errors on set. If for example you were creating a LUT for Arri LogC, keep 18% grey at Arri's recommended 398 so that you maintain 7 stops under and 7 over. Then if you want to rate the camera for one stop more latitude in shadows, set the camera to 400 ISO or if working without a monitor rate your light meter to 400. Also, if you were to create a LUT for awgrgb LogC and you were working in that color managed space, having a LUT that is correctly mapped to LogC's 18% grey means you can transform other cameras / VFX shots into awgrgb logC, apply your LUT at the end and have everything remain consistent.