Shooting log, and when it helps

Somewhere in your camera menu there is a picture profile with log in the name, and somebody on the internet has told you to use it. You tried it once, the footage came out grey and lifeless, and you switched back.

That reaction was correct, given what happened next. Log is not a look. It is a way of recording that holds on to more of what the sensor saw, particularly in the bright parts and the dark parts, and it hands you a flat washed out picture in exchange. The information is all there. It is just not arranged yet.

Decide with whoever will edit the footage. Log can help when the camera and recording format support the intended grade. If the footage needs to be ready to publish with minimal processing, a suitable display-ready profile may be the better choice.

What is log, in plain terms?

A display-ready picture profile applies contrast and colour in camera. Depending on the scene and settings, some highlight or shadow detail may be harder to recover later.

Log encodes the captured tonal range for later processing. Viewed without the appropriate display transform, it looks flat. It preserves flexibility within the limits of the sensor, exposure and recording format.

The trade is simple. Normal profiles make the decisions for you and the decisions are irreversible. Log postpones them and expects somebody to make them later.

When does log help?

Grading has to be true. Difficult lighting is the second, and it decides how much you get back.

Somebody is going to grade the footage. Not apply a preset, grade it: correct it, balance it, treat the shots as material. Log gives that person room to work, especially in recovering a bright window or opening up a face that sat in shadow, and it makes matching several cameras considerably easier because there is more to move.

And the lighting is difficult. A room with a window in the shot, a kitchen with a bright hob and a dark corner, a stage, anywhere the range between the brightest and darkest thing in frame is uncomfortable. That is where the extra detail gets used. In a room with one lamp and a plain wall, there is very little at the extremes to preserve, so log gives you less back, though a real grade and multi-camera matching can still use what there is.

One thing has to be true underneath both. How much latitude log returns depends on the format it is written into: a ten-bit or raw recording gives a grade real room to move, while an eight-bit log profile, common on cheaper cameras, hands back far less than the name promises. If your camera only records eight-bit, test before you commit a shoot to it, because the detail you are shooting log to keep may not survive the file it is being stored in.

When does log hurt?

When nobody is grading, which is most of the time for most people.

Ungraded log is not neutral, it is worse. The picture is flat, the colours are weak, faces look unhealthy, and a viewer is likely to read all of that as poor quality. Upload it as it is and you have made a worse video than the automatic setting would have given you, using more skill.

Log needs careful exposure. Use the camera's monitoring transform and exposure tools where available, and check a test recording before the shoot. A flat preview alone can make exposure harder to judge.

Two smaller costs worth knowing. The heavier formats worth pairing with log take more storage, and underexposed log usually needs noise cleaned out of the shadows, another job you have just given to somebody.

So should you shoot log?

Use these three starting points.

If you edit your own videos and do not currently process log footage, start with a suitable display-ready profile, controlled white balance and good exposure. Put the saved effort into lighting.

If somebody else is grading your footage and they have told you they want log, shoot log, and ask them which profile specifically, because cameras have several and they are not interchangeable.

If you are somewhere between, filming in a difficult room and learning to correct, shoot log on a test only. One recording, both ways, same afternoon, and grade both. That answers the question for your camera and your room, which is the only version of the question that matters.

Where does this decision belong?

Before the shoot, with whoever is going to do the editing, which is the general shape of every good post-production decision.

On one partnership, changing the camera's recording profile gave the grade more room to work. The useful step was a conversation between the crew and the editor before filming. Log footage can also be stored in an .mp4 file; the file extension does not identify the picture profile.

Which is the question worth putting to whoever edits your videos, before your next filming day rather than after it: what do you want to receive? If they have no preference, log is not going to help you, and that answer has saved you an afternoon.

Sources and evidence

What here is established camera and colour-pipeline technique, and what is our own decision rule for whether to shoot log.

What is established. ARRI's own account of Log C and Sony's own explanation of S-Log both describe log as an encoding that preserves more of what a sensor captured, particularly at the bright and dark extremes, in exchange for a flat image that needs a display transform or a grade before it looks right. The Academy Color Encoding System documents the wider colour-managed pipeline this kind of footage is designed to sit inside. Alister Chapman, a working cinematographer who publishes his own camera testing, sets out that how much latitude a log profile actually returns depends on the specific camera and recording format, not on the word log by itself, and that an eight-bit log recording hands back far less than a ten-bit or raw one.

Our method. Shooting log only when somebody is going to grade it properly, and testing a difficult room both ways on the same afternoon before committing a whole shoot to it, is this studio's own decision rule, not a claim that log is always better or worse.

References.

• ARRI. Log C. arri.com. Log C is a scene-referred log encoding preserving captured dynamic range for grading; not display-ready without a transform. Log does not add dynamic range or look correct without a transform.