Transitioning from Video Gammas to LOG/RAW

If you have a modern camera that can record log or raw and has 13 stops or more of dynamic range you need to stop thinking “video” and think “film”.

Alistair Chapman – xdcam-user.com

This scared the hell out of me. Reading a paragraph like this, written by a definite authority on the topic, about the very camera I had just purchased back in 2016. My first HDR camera, the PMW-F5, I was ready, I was keen and thought I knew what I was getting myself in for.

Then, you read that. My film experience is explicitly none. Zero. I’d always been constrained within the realm of video, and it’s broadcast standard constraints. Even further, I had always worked in networks with engineers, who would actually forbid you from changing any setting remotely related to “Gamma” or “Knee”. I, in fact, didn’t even know what these things were or what they did… (Many times I think I still don’t know, I tend to change a setting, see if anything changes at all, then reset it)

Full credit then to Alistair Chapman, whom I had the privilege of getting to study from at a two day workshop he was invited to run at a major network here in London for their staff, and I just happened to be a lucky freelancer there on the same day, and found myself able to be an audience member.

They focused on the FS7 and FS5 cameras, and their Cine/Hypergamma settings, as well as how to correctly expose for shooting in the Sony S-Log 2 & 3 settings. So all the knowledge about “never going over 100% exposure” from my tape Betacam SP days, was destroyed in an instant. Now, it’s a case of don’t underexpose, and a little overexposure isn’t a bad thing! The reason being is that High Dynamic Range cameras like the PMW-F5 retain a hell of a lot of information now in the higher end of the scale, rather than the in the darker end like video did. Only when shooting in CineEI mode, of course.

So then, what are you to do? You’re in the field, you have a HDR camera, and your client has requested the ability to grade the hell out of the raw material that you’ll give them at the end of the day. You only know that skin tones for news gathering should be around 70%, the highlights should be around 90%, and everything else should work out right?

Well, if you’re shooting in S-Log and have that idea, you’re going to give your editor and grader an aneurysm. Your shots will be horrifically overexposed, your dark areas will be devoid of black, and the whole shot just looks a little “mushy”. Your shots looked good in the viewfinder, albeit completely desaturated and a healthy tone of grey throughout. It used to be a case of WYSIWYG (What you see is what you get) but that’s not the case anymore? What are you supposed to do to know how it will look?

Here is the solution.

Use a LUT (Lookup Table) in your viewfinder/monitor which converts it back to REC709 from the Log format you’re shooting in, then shoot as you would have done before using the ‘rules’ you’re used to.

That is really it. You’re simply digitally holding a filter over your viewfinder eye to shoot like a news operator would, sticking to your old, archaic rules and conventions, but the material is being recorded in the S-LOG format at levels that are acceptable to grade with. This technique does require a small amount of preparation before shooting. Here is what you need to do:

  1. Get your client to speak to their editor or grader, and find out what format they want the material shot in, namely S-LOG2, or S-LOG3, or whatever setting they would like for the camera you are using. (I’ll be saying S-Log a log, as an F5 user)
  2. Once you have that information, get a hold of a LUT that converts from the raw format they request, to return it back to REC-709. For example, my F5 has a Sony provided LC-709 “Look” on the camera, but I tend to use a LUT that does the same job provided by Alistair Chapman, whose website can be found at the top of this page.
  3. Make sure you install that particular LUT on your camera, and that you can have it as a monitoring LUT in the viewfinder/monitor. Take special care here, as you can accidentally have the LUT be ‘baked in’ onto the footage, making it no longer RAW/LOG, instead have it be REC-709 out of the camera. This is bad. Make sure it’s set to only be a monitoring LUT, and not a recording LUT. (See two pictures below)
  4. Then, shoot as you would have normally with an old-school video camera. Aim for 70% skin tones, and avoid too many highlights, and should be completely fine. Everything will be within limits.
  5. Lastly, when you send your footage onto your client, send them the LUT file you used for monitoring. Then, their grader/editor has an instant starting point that matches what you saw on the day.
Point 3: Make sure that your Log format appears here, that’s what you’re recording in-camera in the PMW-F5/55.
Point 3: If it says anything like this, then you’re “baking in” your LUT/Look into the footage. That’s generally bad for grading.
This is the monitor output of the PMW-F5 with no LUT applied by the camera. Straight S-Log2. According to the waveform monitor, the middle grey around 32%, and the highest white around 60%. (Sony standard levels at 2000EI on a PMW-F5)
This is the monitor output of the PMW-F5 the 3D LUT applied by the camera, showing that the middle grey is now roughly where it should be, and the whites now hitting 90%, just like standard REC-709 video.

All the talk of “High Dynamic Range” and “Lookup Tables” (LUTs) scared the hell out of me, and frankly still does some days. But it’s far less scary now than it was at the beginning. I’ve completed several shoots now using this technique, and as is standard in our industry, I’ve yet to hear anything back, which generally means it’s not a disaster.

Hope this helps anyone looking to transition from what feels like being a “video peasant” into the “landed gentry of cinema”.

TL;DR – Find the RAW shooting format your client wants. Find a good Look-up-table (LUT) that converts from that RAW format to REC-709, and install it on your camera. Set your viewfinder and field monitor to use the LUT on their display, and make sure you’re still recording in the RAW format of choice. Then shoot like you always have.

PS: If you’re feeling brave, you can actually create your own LUTs by using the great LUTCalc tool created by Ben Turley. Very useful tool covering a hell of a lot of HDR cameras.

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