70D Dynamic Range is actually great, despite what DXOMark says

Started Jan 21, 2014 | Discussions thread
rwbaron Forum Pro • Posts: 14,214
Re: 70D Dynamic Range is actually great, despite what DXOMark says

Just another Canon shooter wrote:

rwbaron wrote:

Just another Canon shooter wrote:

This is a really weird view of the data. You think that you can separate the read noise of the sensor from the read noise of the circuit, whatever those two mean? You are just saying that at high ISO, the two sensors look similar but we knew that.

In any case, at base ISO, the read noise is much worse.

David is absolutely correct. This has been discussed ad nauseam on the Canon forums by some very knowledgeable people. Canon's sensors are actually excellent and may be the best in the industry currently. It's their ADC being off chip that leaves the signal in analog state too long that's the problem.

How does this contradict what I said and what difference does it make? Most of the read noise comes from that circuity anyway, we know that. Amplifier noise is a major part of the "read noise" - Wikipedia. See, it is called read noise, not sensor noise. Unless we have a way to replace the ADC, we take it as a whole, and the results are known.

It does actually make a difference.  To my understanding, prior to the Sony Exmor, the ADC was always located off chip regardless of sensor manufacturer.  At that time Canon's CMOS sensors had a significant advantage and were considered the best silicon in the industry.  Enter Sony with the Exmor where they incorporated the ADC on the sensor chip where the analog to digital conversion happens immediately reducing the noise floor substantially with the benefit realized only at lower ISO's.   Canon currently has no answer for this and still uses an off chip ADC which has a much higher noise floor that penalizes their low ISO DR performance but when you consider read noise at high ISO it is evident that it's not Canon's sensor that's the issue, it's their off chip ADC design and implementation.  As David Hull has pointed out, Canon's sensors (silicon) are actually quite good if not still the best.  If Canon would implement an on chip ADC like the Exmor their overall performance might actually be the best in the industry once again.

Technically it's not the sensor, it's the ADC.

Bob

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