WOW what a game changer A7s

Started Apr 6, 2014 | Discussions thread
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Astrophotographer 10
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Re: WOW what a game changer A7s
In reply to Ontario Gone, Apr 7, 2014

The D4 is in fact a lot cleaner than the D800.  Larger pixels are often associated with lower high ISO noise. Nex 7 is noisier than Nex 6 for example. But yes the 16mp Exmor sensor in so many cameras is cleaner at higher ISO than much earlier Canon 40D for example at 10mp.

With the trend of manufacturers using noise reduction so heavily in camera it blurs this aspect.

There are several sources of noise in a CMOS/CCD setup. Thermal noise, read noise, fixed pattern noise, shot noise, noise from the A/D converter, noise from the amplifiers etc etc.

I take it we are mainly referring to read noise here?

Larger pixels have larger well depth. Well depth and read noise determines Dynamic Range so there is no question the larger pixels (which are probably around 9 microns) should have a larger dynamic range.

As Sony seems to be able to get read noise lower and lower then it is likely it is cleaner from that alone.

Signal to noise ratio comes into it. Its easier for a large pixel to gain a signal above the noise floor and show detail without noise. Smaller pixels take a smaller slice of the signal but may have the same read noise so will show noise earlier as ISO increases.

You may be referring to the fact the read noise may be similar to a larger MP sensor. Sony does not seem to release the read noise stats of their sensors so we have to guess here.

From what I have seen from CCD spec sheets, thermal noise tends to not vary too much between models of sensors. I don't know if that is the case with CMOS sensors.

Anyway no point in arguing about this as sample pictures due out soon will prove it one way or the other.

Greg.

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