From DXOMark: More pixels offsets noise3

Started May 30, 2009 | Discussions thread
Steen Bay Veteran Member • Posts: 7,418
Re: Yes, a bit tricky..

John Sheehy wrote:

Steen Bay wrote:

I still use my 'old' 40D. Can't afford, or justify, to update every
year, but I'm sure that the 50D is the better camera, and I'm looking
forward to a 18-20mp 60D, which I'll probably get. And yes, comparing
cameras and images can be a bit tricky, which all these long threads
should prove

Well, there are a lot of logical traps to fall into. Most people
seem to have a very difficult time adapting one paradigm when they've
already adapted another, and are incapable of recognizing the
superioirity of the new one.

If we had 200MP monitors, we would be viewing the output of all
cameras (and crops we make from them, unless very small and intended
for small web images) full-screen on the monitor. Cameras which had
many more pixels, but softer and noisier at the pixel level, would
look more detailed in a more natural, non-aliased way, and would be
less noisy or the same in most cases.

Printers get us closer to reality (when printing images at the same
size), but they are still flawed in some ways.

Now, higher pixel counts suggest that you may be able to crop deeper
or display/print larger, as is sometimes the case, but the ability to
do so is above and beyond the standardized concept of image quality.
People who expect the same quality doing so are unrealistic; only the
most superior optics, focus, and camera stability, and shooting at
low ISOs, allow that. And the results must be compared to cropping a
lower-density camera just as deeply, or displaying the image just as
large. To use the pixel level as the limit for comparing cropping or
maximum display size is nonsense; the "unity" is an illusion.

Is there really a problem with camera B, because camera A looks
better per unit of displayed area one foot from your face printed
much smaller? That's ridiculous, yet that is the foundation of the
pixel-centrics.

John

Yes, lots of logical traps to fall into. Assuming that bigger pixels are always better, is a bit (just a bit) like assuming that bigger sensors are always better, and forgetting that when shooting at the same shutterspeed and DOF, all sensor sizes will have pretty much the same IQ, because with the bigger sensor, you'll have to use a higher ISO value and (f-number) to get the same DOF.

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tko
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