Standards for HDR have been established by various industry organizations for displays but as yet, no similar initiative has been undertaken in the camera industry, though manufacturers almost without exception make exaggerated claims for the dynamic range of their cameras. It is said that photochemical film is capable of 13+ stops, though this varies greatly depending on the individual stock, and print film has substantially less than the negative itself, perhaps as few as 10 stops. In the filmmaking community, colorists and authorities on HDR regularly toss around numbers like 13, 14 or 15 stops as being necessary for high dynamic range video. Shane Mario Ruggieri, Advanced Imaging Systems Creative Lead at Dolby Laboratories, has said that 10 stops is perfectly fine – provided you’re only interested in grading up to 100 nits! In other words, if our goal is to simultaneously capture detail in the face of a spelunker in a dark cave while still retaining highlight detail at the cave’s entrance or the like, 10 stops would be insufficient. Given all this, is it possible for us to determine a reasonable lower limit that a camera can record and still qualify as HDR capable? We can take a cue from this BBC paper, where it is argued that an HDR display should ideally be able to reproduce what the human visual system is capable of seeing:
“Ideally HDR video should exceed the static dynamic range (i.e. the dynamic range that can be appreciated in a single scene) of the human visual system. So, for video, the dynamic range should be at least 10 000:1 on the final display. A dynamic range that is much greater than 10 000:1 cannot be seen by the human visual system and so is not useful.”
A contrast ratio of 10,000:1 comes out to 14 stops, though many would contend that the human visual system (HVS) is only capable of distinguishing around 12 stops – or even less. Nevertheless, even in low dynamic range video (colloqially known as SDR), it is possible to see the undeniable advantage something like the Canon C70 with 12 stops of dynamic range has over less capable mirrorless cameras like the Canon R5 with 10 stops of dynamic range. Expressed as contrast ratio, 10 stops of dynamic range is equivalent to 1,000:1, far below levels encountered on a daily basis. It should be noted that while clipped highlights of SDR video like those in the comparison can be and often are gently rolled off or diffused in the colorist bay, they are unrecoverable in HDR and concealing them is next to impossible. A simple defintion of an HDR camera would be one that is capable of encoding pixels with over three orders of magnitude, similar to film. Naturally, the camera must also be able to record 10 bits or more.
Photo: Parker Walbeck
Walbeck’s videos look amazing like HDR 709. Especially for run & gun a camera with a DGO sensor would be ideal but for more static scenes you could make do with an inferior sensor and use lighting to balance the scene.