D7200: More Megapixels, more DR, or improved high ISO IQ? Locked

Started Mar 29, 2013 | Discussions thread
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mosswings Veteran Member • Posts: 8,512
You can't always get what you want

mosswings wrote:

jonikon wrote:

mosswings wrote:

The D7100 has taken the only road left to sensor manufacturers until the mad scientists in the labs concoct some new sensing paradigm that is manufacturable: high resolution. If you keep the noise per unit area the same or nearly so, and the well capacity the same or nearly so (as the manufacturers have), the result is a file that can be processed into something far better than the raw per-pixel noise performance would suggest.  The penalty you pay is that you have to postprocess the file, or hope that the in-camera processing has been kicked up a notch.

It is well known that with a given sensor technolgoy the way to more dynamic range is a larger photo respeptor well to gather more photons.   So there is not another road, which is to increase the photosite well size. This can be achieved with current technology by decreasing the number pixels on a given size sensor, allowing a larger well size.
- Jon

Only to the extent that:

1) lithography compromises well areal fill ratio, since sensor noise and dynamic range both scale by area (depth is constrained by epitaxial processing)

2) conversion noise sources (ADC, analog gain stages, etc.) compromise sensel noise/DR properties.

At the current level of technology, these sources are relatively small contributors; further tricks, such as BSI (wiring on the backside), will not result in dramatic gains.  At best they'll nibble at the edges.

The D600 outperforms the D800 at the pixel level by only a small margin. The NEX-5 outperforms the NEX-7 by a similar small margin.  But at the same image resolution, their performance is essentially identical.

To realize the 2 stop performance gains similar to that seen from the D80 to D90 transition, we will have to change bulk technology throughout the sensing chain - losing the Bayer CFA, etc.. And then we're up against the fundamental limit of photon noise.

Let's turn this question around a bit.

A lot of us out there, myself included, are probably saying "all I want to do is take a nice clean 6MP picture.  Why do I need to use a 24MP camera to do it?"

That's a fair question.  I've been rather staggered at the image storage implications of the D7100 on the long photo vacations I often take.  My 144MB of SD cards, good for 10,000 shots on my D90, will store no more than 3500 at the resolution and bit depth that justifies the use of a D7100.  That is an extra $300 of SD cards.

Certainly it would seem that the manufacturers could create a super 6MP EXMOR sensor that would blow the doors off of the D7000.  But the areal nature of sensel noise says no...it would be nearly the same.  Faced with this limitation of bulk processing, what's a manufacturer to do?

Call in the mathematics calvalry, with its version of the Gatling gun, high resolution.

I don't like the ancillary waste of this approach, but until the gods of R&D bestow a new paradigm upon us, it's what we have to work with.

 mosswings's gear list:mosswings's gear list
Olympus XZ-1 Olympus Stylus 1 Nikon D90 Nikon D7100 Nikon AF-S DX Nikkor 18-105mm f/3.5-5.6G ED VR +5 more
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