Breaking the Myth of Megapixels
David Pogue has re-done the test, this time using the zoom on a Canon EOS-1Ds to take photos of the same subject at different resolutions, rather than downsampling using Photoshop. (Also, for some reason the smallest resolution for the test has increased from 5 MP to 7 MP.) I still don’t think this is measuring the right thing. The relevant question is not how a lower-resolution image taken with a high-end camera looks, but rather how the image from a lower-resolution camera compares with the image from a higher-resolution camera. By trying to control for differences in cameras by always using the same camera, the test is failing to measure what it’s supposed to. Before it measured Photoshop; now it measures the zoom lens.
The article’s point seems to be that people with older cameras shouldn’t feel pressured to upgrade to newer (or more high-end) ones. The newer ones have more megapixels, but megapixels don’t really matter. However, accepting the megapixel premise doesn’t prove the point. If megapixels don’t matter, then we should be comparing other factors, such as lenses and sensors. Surely these have improved over the years; they’re just less salient than the number of megapixels. As constructed, the test shows that if you have an EOS-1Ds and want to print at 16-by-24, there’s no need to zoom in on your subject. But if you want to know whether your camera from 2005 is obsolete, you should compare its photos with ones taken by a current camera. The results would only be valid for the two cameras you happened to compare, but at least they would say something about those two cameras. Measuring the zoom on an EOS-1Ds says nothing about your camera or the one the salesperson is showing you.
