Started Jul 11, 2011 | Discussions thread
teodorian2 Senior Member • Posts: 1,870
Re: ok 4 stops DR. Howmany stops ISO?

SNRatio wrote:

brettchris wrote:

Are you sure? I would have thought this is in fact where all the improvements in image quality with new sensors is coming from? Better filters, better pixel sites at smaller sizes is the frontier of electrons developments for cameras - I couldn't let this comment go unchallenged.

I don't think it is possible to uphold image quality uniformly over the ISO range while increasing pixel density, and there is always some loss related to binning. But with ultra-low read noise + eventually some tricks. a 24 MP D400 may well beat the D300s at ISO 100 on a per pixel-basis.

Try to look at the different elements here. Of course, small improvements are still possible, but the huge improvement potentials are already mostly exploited. With a given basis technology, like Bayer, that is. Take "better filters", for example: To improve sensitivity/resolution, they must be made weaker, but then color precision and resistance against artifacts will probably suffer. And the photosites themselves already yield so much that huge improvements are difficult. No sophistication of electronics can create information in a shot noise dominated situation, as we have on high ISO.

If a sensor has already > 0.5 quantum efficiency, there is no way a sensor with half the pixel size can beat it per pixel photon-wise, it can't get higher than 1. If the quantum efficiency is very low, much is possible, but the D3s just isn't there. And it's mostly resolution that can be dramatically improved by shrinking the pixels. The D3s and D7000 sensors are so good that it is hard to beat them very much on a per pixel basis - we will soon see how much withg present technology, I think.

The key phrase here is "uniformly over the ISO range". For example, with modifications that effectively lowers ISO, we can get a lot of quality from very small photosites, but that is of little help in low light. And by pixel binning, we may reconstruct a better image in low light from fuzzy pixel info, but that will be at the cost of resolution.

The improvement is over the whole ISO range and mostly thanks to the increase of MP resulting in better image quality at a given print size despite the the fact that the per pixel quality is not improving much at all.

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