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Successor to Blackmagic Cinema Camera CMOS sensor announced with possible hardware HDR mode


Andrew Reid
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No, two 11 bit ones.

 

Now the question is - how are they used?

 

The older sCMOS chip essentially had these same specs -- including dual 11-bit ADCs. The dual readouts are zero-gain and high-gain, and the two are combined to form one 16-bit signal. The Arri Alexa's sensor has a conceptually similar dual-gain architecture.

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The older sCMOS chip essentially had these same specs -- including dual 11-bit ADCs. The dual readouts are zero-gain and high-gain, and the two are combined to form one 16-bit signal. The Arri Alexa's sensor has a conceptually similar dual-gain architecture.

 

Exact, dual gain 11-bit dac on the current BMCC sensor... so nothing new...

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The older sCMOS chip essentially had these same specs -- including dual 11-bit ADCs. The dual readouts are zero-gain and high-gain, and the two are combined to form one 16-bit signal. The Arri Alexa's sensor has a conceptually similar dual-gain architecture.

 

So what's new? Anything at all? Just better in low light?

 

Oh dear. Not good news for future Blackmagic cameras is it...

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I think after releasing a 4K beast the only thing missing from Blackmagic's camera portfolio is a dedicated high speed camera. That could be a big hit. The sensor size and even the dynamic range is secondary if they could achieve something like 240fps in ProRes/DNxHD @ FullHD.

Of course I would't mind a rev2.0 BMCC with HDR..

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Exact, dual gain 11-bit dac on the current BMCC sensor... so nothing new...

 

But then why is BMCC 12bit raw? Do they just concatenate the extra data? The only thing I could want from BMCC is a slightly bigger sensor, and the accompanying low-light performance. 

 

@eoshd, remember, you said yourself there is no garuntee that these are the sensors going into BMCC updates.  Plus, they could always up the SSD controller, and do crazy things like 16bit raw, or 12bit raw at 4K (pushing up against the write speed of the faster SSDs).

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So what's new? Anything at all? Just better in low light?

 

Oh dear. Not good news for future Blackmagic cameras is it...

 

Peak quantum efficiency improved from >52% to >80%. Low QE was one of the downsides of sCMOS compared to back-illuminated CCDs, but now the gap is negligible. See old specs here http://fairchildimaging.com/catalog/focal-plane-arrays/scmos/cis-2521f

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So what's new? Anything at all? Just better in low light?

 

Oh dear. Not good news for future Blackmagic cameras is it...

BMD don't need more dynamic range. They need a camera with a good form factor and without a million annoying quirks.

There's plenty of room to create a more desirable follow up.

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BMD don't need more dynamic range. They need a camera with a good form factor and without a million annoying quirks.

There's plenty of room to create a more desirable follow up.

 

What BMD REALLY needs is to ship their bloody cameras.  ;)

But I agree. The sensor is the last thing they should be focusing on. How about giving users the ability to... I dunno... review/delete clips? Have a decent battery? Some kind of total runtime countdown? A myriad of basic camera features that any decent company would think to include in a quality assured product. 

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But then why is BMCC 12bit raw? Do they just concatenate the extra data? The only thing I could want from BMCC is a slightly bigger sensor, and the accompanying low-light performance. 

 

@eoshd, remember, you said yourself there is no garuntee that these are the sensors going into BMCC updates.  Plus, they could always up the SSD controller, and do crazy things like 16bit raw, or 12bit raw at 4K (pushing up against the write speed of the faster SSDs).

 

This is what I wrote last may >

 

 

The sensor sampling is done by two ADC - one with high gain amplifier, one with low gain amplifier. Each ADC output 11bit. Two 11bits doesn't give neither 22bits (unless it is MSB and LSB - but it is impossible in this case, amplifier/ADC are linear) The only linear signal that could be created (over 11bit) is a 12bit signal - greatest value of a 11 bit unsigned integer is 2048, 2048+2048=4096=12bit. Over that, it is not linear anymore... but logarithmic. If the high gain was +18db, you need to multiply its ADC output by 3. I will not go deeper, but hope you understand...

 

However, from the measured specs, a ratio of 16,000:1 is best represented by a 14bit linear value. +/-13 stops is best represented by a 14-bit linear value. However I think that BMCC did a better choice of choosing 12bit log instead of 14bit linear.

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