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I use Sony Nex 6 and I noticed that on not really high ISO (let's say 1600) pictures get discernibly grainy. Also I know that the next's model main feature is larger image size (24MP comparing to 16MP on Nex-6).

So I'm trying to wrap my head around if larger image size may result in better ISO sensitivity (so images get less grainy)?

Dmitry
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So I'm trying to wrap my head around if larger image size may result in better ISO sensitivity (so images get less grainy)?

It actually tends to work the other way: larger photosites give better low-light performance because each site has more photons falling on it.

So if you have two sensors with the same physical dimensions, the one with the lower pixel count will generally yield a less noisy (but lower resolution) image. Or, if you have two sensors with the same pixel count but different physical dimensions (e.g. APS-C and full frame), the larger sensor will offer better low-light performance.

The numbers for those two models bears this out. Your NEX-6 offers ISO settings all the way up to 25600, while the NEX-7 only goes up to ISO 16000.

Caleb
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  • " larger photosites give better low-light performance because each site has more photons falling on it. " - I'd say that it occurs because of increased fill rate, not because of photon number per pixel increase. – Euri Pinhollow Mar 18 '16 at 13:35
  • It's also worth to mention that cameras with high MP count get better dynamic range at base ISO as higher MP count helps to overcome current 14bit ADC limitation. – Euri Pinhollow Mar 18 '16 at 13:38
  • It's also worth noting that it's not just pixel size, but that improvements in sensor design / manufacture also come into play - newer sensors are more likely to outperform older ones even with a larger pixel. – James Snell Mar 18 '16 at 22:46
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    @PinhollowEuri It occurs because the increased numbers of photons striking each pixel well allow a lower noise floor, which is pretty much the same thing as saying increased dynamic range. The larger surface area also reduces photon shot noise by averaging the randomness more on a per-pixel level. – Michael C Mar 19 '16 at 03:31
  • Larger sensor size gives less grainy images because it has more sensitive elements which consume photons thus result in a more dynamic image range. If we continue speaking about Sony Nex 6 and 7 models AFAIU because Nex-7 model sensor size remains the same the larger image size (24MP) is achieved due to pure scaling like digital zooming? – Dmitry Mar 19 '16 at 17:33