Andrew Reid made this nice lowlight capability comparison between the new Canon 5D mark III, last year’s lowlight wonder the Sony FS100 and the all-time classic Panasonic GH2 camera.

Three test scenes shot in dark rooms at a ex-factory building in the east of Berlin. Minimal lighting – in scene 1, pearly strip light, scene 2 is iPhone torch, scene 3 is a reflection of petrol station lights in a mirror.
Lenses – Leica R 35 2.8,50 F2,90 2.8 (apart from scene 2 which is Samyang 24mm F1.4 on both cameras)
The 5D Mark III used here is modified. The OLPF (anti-aliasing filter) and IR-cut filter is removed for a resolution increase bringing it closer to the Sony FS100 and Panasonic GH2. No sharpening in post required. Sharpening in-camera was turned off. All footage direct from card, no grading. Edited in Adobe Premiere Pro CS6.
1st scene is to test noise and resolution.
2nd scene is to test ISO 12,800 performance.
3rd scene is to test handling of highlight and noise in the lows

via EOSHD