Frame rate and play off of 12-bit, 14-bit, 16-bit

[Mikehit]

Following the announcement of the D850, there is chatter about Canon's response and some of this has been on the level of MP and frame rate. If any manufacturer shows any step back on anything regards image quality they get a hail of abuse irrespective of the practical consideration and the area of the market the camera is aimed at.

I have zero understanding of the technicalities of processing power vs downsides such as heat sinking, but how far can we go with the 5DSR mk2 - if it were to appear - offering higher frame rates? Could they take a leaf out of Sony's book and do so by dropping from 16-bit, 14-bit or 12-bit and is there any noticable effect on image quality. Or, more exactly, under what circumstances would a difference become obvious?

 

[Sporgon]

In actual practice, rather than theory, I don't see any difference between 12 and 14 bit files. I remember reading somewhere - it may have been Clarke Vision, or possibly Bill Claff, why there is very little improvement in going from 12 to 14 bit, but I can't find it now.

Anyway, give me the 12 bit option for more speed and I'd take it.

 

[hne]

Following the announcement of the D850, there is chatter about Canon's response and some of this has been on the level of MP and frame rate. If any manufacturer shows any step back on anything regards image quality they get a hail of abuse irrespective of the practical consideration and the area of the market the camera is aimed at.

I have zero understanding of the technicalities of processing power vs downsides such as heat sinking, but how far can we go with the 5DSR mk2 - if it were to appear - offering higher frame rates? Could they take a leaf out of Sony's book and do so by dropping from 16-bit, 14-bit or 12-bit and is there any noticable effect on image quality. Or, more exactly, under what circumstances would a difference become obvious?

You need one bit per stop of DR plus some leg room for preserving noise to facilitate better noise reduction. Both Nikon and Sony ignore the latter and divide sensor readout values by the black point, in essence shifting bits to the right* so that fewer bits are needed. Sony even goes so far as to apply noise reduction before writing the raw file, resulting in angry astrophotography people losing stars in their images.

Modern FF sensors need at least 12 bit raw files just for DR. The difference in file size to 14bit is way less than the 14% you could be lead to believe would be achievable. The raw file also contains a thumbnail, preview, metadata, headers, ... Canon would be able to achieve something in the ballpark of 14% increase in write speed most easily by not including a high quality full resolution jpeg embedded in the raw file. That's right - when you set your camera to raw+jpeg, the jpeg data is written twice.

* For the technically proficient readers: laymen prefer MSB left without further explanation.