How do i explain to someone its not about megapixels ?

Started Oct 4, 2013 | Questions thread
John1940
John1940 Senior Member • Posts: 2,820
Re: the cult of DPR
1

bobn2 wrote:

dholl wrote:

bobn2 wrote:

What it says is if you had the EXIF you might well find that the answer was what you expected. Without the EXIF, you don't expect anything.

right...very good then.

The images really are still there, and they really are DPReview's test scene at 25,600 ISO with a D800, a D600 and a D700.

Production economics more than technology.

...in your opinion.

which is a better opinion than your opinion, in my opinion. Better as in better informed.

It would also balk at a camera which introduced very poor results in brighter light.

Who's making sensors like that and why would they? You're just making the same point I'm making.

The saturation capacity of a CMOS sensor is dictated by its voltage output swing and its charge/voltage characteristic. The charge/voltage characteristic dictates the read noise. This sensor has a huge collection area per pixel and a large charge/voltage and therefore will have a very low per area saturation capacity, that means low high light DR. That's why Canon doesn't build this sensor into all of its cameras, it is specially made for low light video surveillance.

It is designed to be ultra noise-free at high ISO and low-light, to do that it needs very large and very few pixels on a full-frame sensor. They can't reach the same quality-of-sensitivity if they packed ultra-HD on there (8mp).

It's all to do with the read noise. They made the sensor to match the requirements of a particular application.

That doesn't tell anyone anything. You're avoiding the question: could Canon have made that same sensor but with 8mp instead of 2mp and still keep the same quality of lowlight performance?

No, but they couldn't either build a sensor that size with that few pixels that had decent low light performance. As I said, it's all about the read noise, more specifically the balance of charge collection area versus charge/voltage characteristic. They've just made a choice which effectively raises the base ISO of the sensor, probably to something like 1600 ISO.

Production economics more than technology.

...in your opinion.

which is a better opinion than your opinion, in my opinion. Better as in better informed.

It would also balk at a camera which introduced very poor results in brighter light.

Who's making sensors like that and why would they? You're just making the same point I'm making.

The saturation capacity of a CMOS sensor is dictated by its voltage output swing and its charge/voltage characteristic. The charge/voltage characteristic dictates the read noise. This sensor has a huge collection area per pixel and a large charge/voltage and therefore will have a very low per area saturation capacity, that means low high light DR. That's why Canon doesn't build this sensor into all of its cameras, it is specially made for low light video surveillance.

This post and the above paragraph are very useful and interesting for folks like me. Photography has been a major hobby for me for over 50 years but I always shied away from developing film because I liked mathematics and physics more than chemistry. (I was mostly a Kodachrome user.) The advent of digital photography and video came at the right time for me, i.e., fairly late in life. Keep up the great work in explaining how sensors and other parts of my cameras function.

I'm sure that I know how sensors work (not as well, probably, as someone like Eric Fossum, but better, in all probability, than someone like you)

The inventor of the CMOS sensor very likely might join this thread and answer the 8mp question (or this thread might need to be moved into the Science-Tech forum).

The inventor of the CMOS sensor, so far as I'm aware, doesn't post on these forums. Eric invented the active pixel sensor.

I'm not getting into a who-knows-more-about-sensors willyfight. I'd just like that question answered reliably, for it helps the OP's case.

Where 'reliably' means an answer that you agree with.

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Bob

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John1940

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