Sensor performance, quantum efficiency, sensorgen and DXOmark

Started Feb 5, 2014 | Discussions thread
rrccad Forum Pro • Posts: 11,228
Re: Peak QE of the 70D

Jack Hogan wrote:

rrccad wrote:

Jack Hogan wrote: As for pixel pitch, Raw Digger shows 5568x3708 including the masked pixels and 5496x3670 for a 70D sensor size spec'd at 22.5x15mm. That would yield pitches of 4.045 and 4.09 microns respectively. I wonder whether manufacturers spec the size of the sensor including masked pixels? Using the masked pixel count and 550nm peak QE by Chris' method is 50.9% and 49.1% at ISO800 and 1600 resp.

except with the 70D I would suspect the pixel pitch is actually lower with each pixel being split in half.

which makes canon raising the QE by nearly 10% even more remarkable.

Yes, but keep in mind that when we speak about QE here we are not just talking charge collection efficiency and fill factor. The photosite sits under a microlens and various filters (including AA, CFA, IR) the combined effects of which make up the lion's share of what is being termed 'peak QE' in this thread. It's much easier for instance to weaken the CFA in line with current trends then to change/improve fabrication technology. And we know that doing that results in compromises elsewhere...


yes, but canon did that around the 7D / 60D / 18Mp sensor level - weakened the CFA?

canon obviously had to change fab technology somewhat to accommodate 40mp PD's on a APS-C sensor.

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