FX3 In-Camera False Color LUT

Why make this LUT?

Like many other cinematographers, I was frustrated when Sony released the FX3 and gave it the "Cinema Line" moniker but declined to add essential tools and feature such as false color monitoring and shutter angle. Sure, you can obtain false color readings with an external monitor but to me, this defeats the purpose of the strength of the FX3: it's small footprint and size.

When thinking of potential workarounds, I realized that at the lowest level, a false color reading is assigning a new color value to a pixel depending on what its luminance value is— which is something that a LUT can do very well.

What is this LUT?

This is a 17x17 false color LUT that can be loaded into compatible Sony cameras and assigned to the FN menu for quick access and exposure checks. It is only compatible with SLOG3 & sGamut3.cine. Use with any other gamma & color space will result in an inaccurate reading.

How do I install this LUT into my FX3?

Sony's intructions for install

How do you assure exposure accuracy with this LUT?

A false color LUT is useless if it doesn't provide an accurate exposure reading. To assure accuracy, the false color LUT needs to do some things is a specific order.

Behind the scenes, the LUT first takes your SLOG3 image and normalizes it using Sony's official SLOG3 to Rec709 LUT. Once a normalized image is obtained, the LUT reads the exposure values of the image and assigns new color values to the pixels depending on what their luminance values are— resulting in a false color reading.

It was important that the LUT reads a normalized image and not a LOG image which was a bit of a challenge to do.

What false color scale is used in this LUT?

I opted to go with using Blackmagic Design's false color scale as I felt it is the easiest to read and understand at quick glance. I have worked extensively with BMD cameras and felt that the false color scale was just an overall better choice than the false color scales of companies like RED, Atomos, etc.

BMD False Color Scale used in this LUT

Is the LUT accurate?

To prove this LUT is accurate, I performed a test below, exposing the subjects face using my light meter. When exposed with a light meter, caucasian skin should generally fall around +1 stop above Middle Grey and should show as pink in the false color scale used in this LUT.

When applied, the false color LUT reads the image accurately and correctly assigns pink to the subjects skin, proving its accuracy.

Reading from camera using this False Color LUT

I hope this is useful to other cinematographers out there, this has been super useful to me on set!

Thanks!