Sensor bit readout and rolling shutter

[Abevideo]

Fujifilm says "..the X-H2S produces its 6.2K and 4K up to 30p from 14-bit readout, rather than 12-bit mode on previous cameras, meaning the camera can detail up to an extra 2 stops of dynamic range in video mode."

 

and. "Despite the higher bit-depth of the 30p (and slower) modes, Fujifilm says the X-H2S offers rolling shutter rates of around 10.6ms in F-Log 2 mode, quicker than the 16.6ms rate of the X-T4. The higher frame-rate modes, or use of the original F-Log profile, see the camera use a 12-bit readout mode, delivering rolling shutter of 5.6ms."

 

 

I don't quite understand...

 

1. does this mean all Flog '1' only uses 12 bit sensor readout, even at lower shutter speeds?

 

2. presumably having higher frame rates than 30p mean you only have 12bit sensor readout...so does it then improve the sensor readout speed and rolling shutter?

 

and then subsequently, 3. If flog2 is used above 30p, and it does convert to 12-bit sensor readout, does it lose the '14 stops' of dynamic range?

 

If anyone knows it would be really helpful

[ChrisKou]

On 10/4/2023 at 7:01 AM, Abevideo said:

1. does this mean all Flog '1' only uses 12 bit sensor readout, even at lower shutter speeds?

I can say yes to this question. F-Log is 12bit readout at all speeds. I use it for when I need faster readout (fast action and lots of camera movement), and it does great.

I'm not sure as to the other questions. I would be interested to hear what people know about those.

Chris

[Abevideo]

Thanks. The rest remains a mystery… 

[Abevideo]

Thanks. The rest remains a mystery… 

[Omen]

On 10/4/2023 at 2:01 PM, Abevideo said:

 

1. does this mean all Flog '1' only uses 12 bit sensor readout, even at lower shutter speeds?

Yes.

On 10/4/2023 at 2:01 PM, Abevideo said:

2. presumably having higher frame rates than 30p mean you only have 12bit sensor readout...so does it then improve the sensor readout speed and rolling shutter?

Yes.

Less data to read, faster readout.

 

On 10/4/2023 at 2:01 PM, Abevideo said:

and then subsequently, 3. If flog2 is used above 30p, and it does convert to 12-bit sensor readout, does it lose the '14 stops' of dynamic range?

Probably.

[Paul Szilard]

Quoting from DPREVIEW https://www.dpreview.com/reviews/fujifilm-x-h2s-review

Quote

Capture bit-depth can limit the dynamic range of a camera, and most cameras drop from 14-bit capture to 12-bit capture when they move to their video modes. The X-H2S can shoot 6.2K or 4K at up to 30p from 14-bit readout in its F-Log2 mode and increases base ISO by 1EV to capture additional highlight information (which inevitably means every other tone is made from less light, and hence will be noisier). The 14-bit readout rate is slower than the camera's other modes but still faster than the X-T4's 4K.