The Core Mathematical Difference
When Canon introduced the Cinema EOS system, they created two logarithmic gamma curves that solve two completely different problems. Beginners often assume "C-Log2 has a 2 in it, so C-Log3 must be the upgrade." That misconception causes hours of painful post-production noise reduction.
Canon Log 2 (C-Log2): Designed to emulate analog negative film (Cineon curve). It dedicates a massive portion of its 10-bit code values to the bottom stops of dynamic range. On a dual-gain sensor like the C70 or C300 Mark III, it delivers 16+ stops of dynamic range. However, because deep shadows are pulled upward, any sensor noise is magnified unless you ruthlessly overexpose.
Canon Log 3 (C-Log3): Compresses shadow values with a tighter toe curve, while retaining identical highlight latitude to C-Log2. It delivers approximately 14 stops of dynamic range. The advantage? Deep shadows stay pinned down near black, resulting in clean, noise-free footage straight into a Rec.709 transform LUT.
If your scene has controlled lighting or you are shooting high-contrast daylight exteriors, shoot C-Log2 exposed at +1.0 EV above nominal. In post, pull down your master exposure node by 1 stop. This pushes any sensor thermal noise deep into zero luminance where the human eye cannot detect it, leaving you with pristine cinema-grade skin tones and intact skies.
Official Canon IRE Exposure Benchmarks
Never guess exposure by eye on the camera LCD. Calibrate your waveform monitor or false color tool using Canon's official engineering reflectance values:
| Reflective Target | Canon Log 2 (Nominal) | Canon Log 3 (Nominal) | Recommended Field ETTR |
|---|---|---|---|
| 18% Middle Grey Card | 34 IRE | 38 IRE | 42 – 45 IRE (+1.0 EV) |
| Caucasian Skin Tone | 45 – 50 IRE | 50 – 55 IRE | 55 – 60 IRE |
| 90% White Card | 73 IRE | 75 IRE | 80 – 82 IRE |
| Sensor Clipping Point | 100 IRE | 100 IRE | Do Not Exceed 95 IRE |
When to Choose C-Log2 vs C-Log3 in the Field
- Shooting narrative cinema, commercials, or music videos with full lighting control.
- You have dedicated post-production time for noise reduction and node-level color management.
- The scene has intense dynamic range (e.g., direct sun blazing through interior windows).
- Shooting documentaries, corporate videos, live events, or quick client turnarounds.
- Working in low-light environments without high-power key lights.
- Editing natively in consumer NLEs (CapCut, Premiere Pro Lumetri) where heavy noise reduction slows playback.
Download Official Canon C-Log to Rec.709 LUTs
Calibrated transforms for Cinema Gamut to Rec.709 Wide DR and film print emulations. Perfect for Premiere, DaVinci, and Final Cut.