Too many megapixels? Six is enough for an 8x10.

Started Apr 26, 2009 | Discussions thread
ejmartin Veteran Member • Posts: 6,274
Re: Insults never a good thing

strawman_John wrote:

So what happens as you add more pixels for a given sensor size. There
is strong evidence that dynamic range is reduced. Take the 50D,
despite it having a later sensor design and better micro lenses, plus
a later generation of processing software and silicon, it has less
dynamic range than the 40D. (For a fairer comparison take some 500D
images and compare to the 40D, without the improved micro lenses it
makes a more comparable baseline).

What is this strong evidence? News for you: DR is about noise. Noise is scale dependent. Pixel DR has little to do with image DR, for the reasons already explained in this thread; DR is a scale dependent quantity, since noise is a scale dependent quantity. The 50D and 40D have about the same DR at the same image scale.

Then I reflect back on my own experience. There are lenses out there
that the 40D can get close to out-resolving, and there is reasonable
evidence of the 50D doing so on more lenses. So I see evidence of the
point of diminishing returns coming in crop sensors.

So using poor lenses and poor technique is a reason for those of us who don't not to have the benefits of higher resolution? No thanks.

So to impress me, make an APS sensor of @ 12mp with noise performance
at ISO1600 of a 40D at ISO200. More pixels, of limited use, unless
the L series range are going to be rolled over, and even then, can I
use the extra resolution????

The noise performance at ISO 1600 is actually better than at ISO 200 with either the 40D or the 50D. It's just that for the light levels it is used for, the signal is weaker, hence the S/N is lower.

If you knew what you were talking about, you would want at ISO 200 the noise performance of ISO 1600 of a Canon DSLR (my choice would be the 1D3, not the 40D; less pattern noise)...

http://theory.uchicago.edu/~ejm/pix/20d/tests/noise/noise-p3a.html

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