Size matters -- not megapixels

In my film camera days, a roll of 35mm film gave you a negative of 36 x 24mm. That area was the "recording surface" for the images I shot.

Digital cameras today are promoted for having 8, 10, or 12 megapixels. That's not the size of the recording surface; it's geek-speak for the number of tiny recording cells on the sensor.

You can squeeze millions of these cells on a sensor. But if the sensor itself is only 7.2 x 5.3 mm -- typically the size found in a pocket digital camera -- you have less overall area in which to capture an image. Add megapixels, and you're just squeezing more tiny cells on a small sensor, which leads to image degradation in the form of "noise."

So, when you're looking at different cameras, megapixels are irrelevant. It's the size of the sensor that really determines image quality. There's a semi-technical explanation of this at this web site, and a simpler (and somewhat exuberant) discussion on Ken Rockwell's website.

Most times, you don't find sensor sizes printed on the camera package. You find megapixels. But here's what I've found:

  • A 1/1.8 sensor generally captures more-detailed, less-noisy photos than cameras equipped with a 1/2.5 sensor.
  • Cameras with 1/1.8 sensors include the Canon A630, the Kodak C875, and Panasonic FX-150. They cost a little more than cameras with smaller sensors.
  • Cameras with (smaller) 1/2.5 sensors include the Canon A590IS, Olympus FE-350, Casio EX-V8 (a personal favorite), and most ultra-compact pocket models from Canon, Kodak, and Nikon.
Deal alert: Canon's factory-refurbushed A630 (a camera I own and enjoy) can be purchased from their web site for $149. That's much less than I paid for it new.

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