S-Log3 color grading in DaVinci Resolve

How do you color grade S-Log3 in DaVinci Resolve?

Correct exposure and white balance on a first node, then add a Color Space Transform set to Input Color Space Sony S-Gamut3.Cine (or S-Gamut3, whichever you shot), Input Gamma Sony S-Log3, Output Color Space Rec.709 and Output Gamma Gamma 2.4, with tone mapping on. Contrast, skin and the creative look all go after that node.

That is the whole recipe. The rest of this guide is about the details that decide whether it works: which gamut your camera wrote, where middle grey should sit, and the handful of problems S-Log3 footage brings with it.

S-Log3, S-Gamut3 and S-Gamut3.Cine: what each one is

Sony's log profiles have two halves, and Resolve asks for each one separately.

• S-Log3 is the gamma curve. It decides how brightness is encoded: flat, with lifted blacks and compressed highlights, so the file holds the camera's full dynamic range.
• S-Gamut3 and S-Gamut3.Cine are the colour spaces. They decide how saturated a colour the file can describe. S-Gamut3 is the wider of the two. S-Gamut3.Cine is smaller, sits closer to the DCI-P3 cinema gamut, and is generally the easier one to bring into Rec.709.

On many Sony bodies, picture profile PP8 defaults to S-Gamut3.Cine/S-Log3 and PP9 to S-Gamut3/S-Log3. Profiles can be edited, though, so a profile number proves nothing. Check the gamut setting on the camera, or open the .XML sidecar file Sony writes next to each clip, which records the gamma and gamut used.

Picking the wrong gamut is the most common S-Log3 error, and it is sneaky: contrast looks correct, but hues and saturation drift, most visibly in skin and foliage. S-Log2 is also a different curve from S-Log3, so do not treat them as interchangeable either.

Step 1: Expose S-Log3 for 41 IRE middle grey

Sony's S-Log3 specification places 18% middle grey at 41 IRE and 90% reflectance white at 61 IRE. Put a grey card in the frame, open the waveform, and land it on 41. That is “correct” exposure for the curve.

Many shooters deliberately rate S-Log3 brighter, up to about a stop over, because S-Log3 shadows get noisy quickly, especially on older sensors. That is a valid choice as long as the highlights are not clipping. Whatever you choose, be consistent across the shoot, and pull the exposure back to normal in the grade before the conversion.

Three in-camera settings decide how much the file can take:

• Base ISO. S-Log3 raises the minimum ISO on most Sony bodies, often to 640 or 800, and dual-base bodies add a second, higher base. Check the manual for your model and stay on a base where you can.
• 10-bit. Log spreads tonal values across the file. 8-bit S-Log3 has too few steps left once it is stretched, and skies and soft walls band.
• Cine EI caveat. On cameras with a Cine EI mode, raising the EI brightens the monitoring LUT, not the recording. If you exposed to a bright LUT at a high EI, the actual file will be darker than it looked on set.

Step 2: Convert with a Color Space Transform

On the Color page, add a serial node after your correction node (Alt+S on Windows, Option+S on Mac), drag Color Space Transform from the Effects library onto it, and set:

• Input Color Space: Sony S-Gamut3.Cine, or Sony S-Gamut3 if that is what you recorded
• Input Gamma: Sony S-Log3
• Output Color Space: Rec.709
• Output Gamma: Gamma 2.4 (see the Rec.709 guide for when 2.2 makes sense)
• Tone Mapping Method: DaVinci or Luminance Mapping, so the extra stops roll off instead of clipping
• Gamut Mapping Method: Saturation Compression, which helps with neon, stage lights and saturated LEDs

If you prefer project-wide colour management, go to File > Project Settings > Color Management, set Color science to DaVinci YRGB Color Managed and the output to Rec.709 Gamma 2.4. Then right-click the S-Log3 clips on the Color page and set their Input Color Space to the matching Sony S-Gamut3.Cine/S-Log3 entry. On multi-camera projects this is the cleaner route, and it is covered in the general LOG workflow.

A third, more advanced option is to transform S-Log3 into DaVinci Wide Gamut / DaVinci Intermediate with one CST, grade there, and convert to Rec.709 with a second CST at the end. It gives every camera the same working space, but on a single-camera YouTube project the one-CST tree above is plenty.

Should you use Sony's S-Log3 to Rec.709 LUT instead?

Sony publishes free conversion LUTs for S-Log3, including the LC-709 and LC-709 Type A looks, and Cinema Line cameras offer s709. They are a fine starting point, and LC-709 Type A in particular is popular for its softer contrast. The catch is that a LUT is a fixed table: it assumes the shot was exposed to Sony's spec, and it clips anything outside the range it was built for.

So if you rated S-Log3 a stop bright, a LUT will look a stop bright until you correct upstream of it. The Color Space Transform does the same conversion mathematically and lets you choose how highlights roll off. If you do use Sony's LUT, put it on its own node after the correction node. The LUT guide covers the trade-off in more depth.

Step 3: Correct before the conversion

Exposure and white balance belong on the node before the CST, while the image is still log-encoded. In log, the Offset wheel behaves much like an exposure change, moving the whole signal up or down without bending the curve, so it is the cleanest way to normalise a shot you rated bright. Use Temp and Tint on the same node for white balance.

After the CST, add a node for contrast (a gentle S-curve or the Contrast and Pivot controls), then one for secondaries, then the look. Correct, convert, shape, isolate, style: the same order as every log format.

Step 4: Fix the problems S-Log3 tends to show

• Noisy shadows. Usually the result of exposing at or below 41 IRE in a dim scene. Lift less, accept slightly deeper blacks, or use temporal noise reduction, which needs Resolve Studio (see free vs Studio).
• Green or yellow skin. Many shooters find Sony skin converts slightly green or yellow, particularly under LED or mixed light. Isolate the face with a qualifier, check it against the vectorscope's skin tone indicator, and nudge the hue toward red rather than warming the whole frame.
• Clipped saturated colours. Blue LEDs and red signage can exceed what Rec.709 can show. Turn on gamut mapping in the CST, then use a Hue vs Sat curve on the offending colour.
• Banding in skies. Almost always 8-bit recording. Light grain or a touch of noise reduction can hide it, but it cannot be fully fixed in the grade.

Common S-Log3 mistakes

• Setting the CST to S-Gamut3 when the camera recorded S-Gamut3.Cine, or the reverse.
• Putting a creative LUT built for Rec.709 directly on unconverted S-Log3.
• Rating the footage bright on set, then fixing exposure after the conversion.
• Shooting 8-bit S-Log3 on a scene with large, smooth gradients.
• Stacking Sony's LUT and a CST, converting the image twice.

A proper conversion and skin tone pass is part of every finished edit I deliver. See YouTube video editing, or compare with the Panasonic V-Log workflow, which follows the same shape.

FAQ

Is S-Gamut3.Cine better than S-Gamut3?

Neither is better. S-Gamut3 is wider, while S-Gamut3.Cine is smaller and closer to DCI-P3, which makes it easier to bring into Rec.709. What matters is that the Color Space Transform input matches the gamut the camera actually recorded.

What IRE should S-Log3 be exposed at?

Sony's specification puts 18% middle grey at 41 IRE and 90% white at 61 IRE. Many shooters expose up to about a stop brighter to keep shadows clean, then bring exposure back down before the conversion.

Can I grade S-Log3 in the free version of DaVinci Resolve?

Yes. The Color Space Transform, Resolve Color Management and LUTs are all in the free version. Temporal noise reduction and Magic Mask, which help with noisy S-Log3 shadows and skin isolation, need DaVinci Resolve Studio.

Why does my S-Log3 footage look dark after the Color Space Transform?

Usually it was underexposed, or it was monitored through a brightened LUT at a raised Cine EI, which does not change the recording. Raise exposure with the Offset wheel on a node before the transform rather than after it.

Should I use a LUT or a Color Space Transform for S-Log3?

In DaVinci Resolve, use a Color Space Transform. It converts S-Log3 mathematically and can roll highlights off gently. Sony's conversion LUTs work, but they expect exposure to match Sony's specification and clip anything outside their range.