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More megapixels doesn't mean better quality.
It's time to blast away some preconceptions about image quality and pixel count on digital cameras.
Over the last couple of years I've made a lot of noise about noise—the digital kind—and how compact digital cameras with high-megapixel sensors are the main culprit.
But let's say you've already bought a camera with 8, 10, or 12 megapixels. If you've been paying attention, you already should know that at the higher speeds the images will be blurry, splotchy and grainy, but what happens at the lower speeds? Can you make a smashing enlargement if you do all you can to optimize overall image quality? And at what ISO setting does image quality actually begin to suffer?
This week, I'll show and analize the results of extensive tests I've run comparing compact digital cameras at different ISO settings so we can see what happens at the lowest, highest and mid-range ISOs on a range of cameras with different pixel counts.
I think the results may surprise you—some of the results surprised me!
How we did it
First, let's look at our test model, Patient Patricia. I photographed her with four different cameras, an 8MP, 10MP, 12MP, and a 12MP camera that claims to have internal noise suppression software. I lit her with a pair of Flashpoint studio lights, using only the modeling lights. Each camera was placed on a steady tripod, and set to record with the white balance set to incandescent bulb.
I used the self-timer on each photo to minimize any camera shake that might come from pressing the shutter release, and disabled any anti-shake features. Since not every camera had manual focus and/or exposure, I chose spot autofocus and spot metering, and used Patient Patricia's eye as the focus/metering target.
Patricia's surface is colored to mimic Caucasian human skin; I added the black hat since grain tends to announce itself first in darker areas of the image. Then I photographed her with each camera at each ISO setting, from lowest to highest.
A few caveats
There are several variables that were beyond my control: each camera had a different lens, and quality consistency is not a guarantee. I learned as I shot that each camera's white balance settings worked differently, so color balance varied from camera to camera although lighting remained consistent. And the size of each camera's spot focus/metering targets varied.
Also, I forgot to comb Patricia's hair right before the shot and some of it got in front of her eye. My bad. (Or maybe not so bad…the strands of hair are good indications of sharpness!)
The devil's in the details
To compare sharpness and grain on midrange subjects, we'll be spending a lot of time looking at ol' Pattie's right eye, shown at 100 percent right out of the camera. There's plenty of fine detail there.
We'll look at the comparisons at different speeds and pixel counts, and we'll dice and slice the results and look at them in different ways.
The result of all of this effort? By the end of this week, you should have a much clearer picture of the kind of overall image quality you can expect from compact cameras of different pixel counts at different ISOs.