More megapixels, better photos: Fact or fiction?

Started Feb 7, 2008 | Discussions thread
Anastigmat Forum Pro • Posts: 12,664
Re: More megapixels, better photos: Fact or fiction?

newsshooterjim wrote:

The article listed pretty well answers the question. The short of it
is that smaller photosites see less light, this means the signal has
to be amplified more in order to get it up to an acceptable level.

The signal only has to be amplified for high ISO settings. Bigger photosites means a stronger signal, even at the base or native ISO. Since background noise is the same, all else being equal, a stronger signal means a better S/N ratio. Of course this is painfully obvious when the signal is amplified, but the difference is there even at base ISO without signal amplification.

Unfortunately, it's just like a tv amplifier. Boost the signal, you
boost the noise. In low light, my 6mp beats my 10mp K10 every time.

One caveat, some manufacturers are finding ways to work around this,
as you can tell if you've seen the high ISO shots from the D3, and to
a lesser extent, the K20.

The D3 is basically doing what Nikon has been doing, using software to lower noise at high ISO settings. Comparing the Canon 5D with the D3, one can see this very easily. The D3 has lower noise at high ISO settings, but less detail. The article cited Canon as claiming that its 10mp sensors have similar sized photosites as its 8mp sensors (they also have better microlenses), but the bottom line is that such advances are also available to full frame sensors, so a larger sensor will always have lower noise, all else being equal.

Plenty of light, more megapixels is fine, less light, it's a problem.
For me, the bigger problem is the myopic plastic they're passing off
as lenses.

Jim Dean
Paid professional rubbernecker. I stop at the car wreck so you don't
have to.

As any photographer knows, too much light is a nice problem to have. In general, most photographers have to struggle with too little light in most situations. Therefore, in most situations, larger pixels beat more pixels for most photographers.

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