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agiaccio Jan 11, 2005 12:15 PM

What affect (if any) does the CCD size (e.g. 1/1.8 on Olympus C-7070WZ versus 2/3 on Olympus C-8080WZ) have on image quality?

ecm Jan 12, 2005 12:50 AM

In general, a larger CCD means larger photosites (ie. "Pixels"). CCD technology in smaller prosumer cameras is very sophisticated; there's a lot going on at each pixel, to provide live preview, etc, so there's a lot of circuitry at each photosite. The smaller the sensor, and the more photosites crowded on, the smaller each photosite is. For a variety of reasons (the physics of light and silicon circuitry, mostly) the smaller photosites are more susceptible to noise; there's been a definite deterioration in picture noise levels over the last couple of years because of the "megapixel race".

That said, some of the newer sensors (and some of the latest camera software noise reduction algorithms), have been improving; for instance the new 7.4 Mpixel 1/1.8" Sony sensor (in a lot of the 7 Mpixel cameras right now) is a very nice sensor, with generally lower noise levels than the previous 5.2 Mpixel 1/1.8" sensor.

Another issue with smaller sensors is the focal length - smaller sensor = smaller focal length. That means smaller lens size, and less tolerance for minute defects. Chromic aberration ("CA" or"purple fringing" and other effects) becomes harder to control as the lens gets smaller. Manufacturing truly high-quality small lenses is difficult; they're not just small, they're minaturized.

What does all this mean, practically? Really, not as much as all that. There's a noticable difference between, say, a 1/1.8" or 2/3" and any of the digital SLR sensors, because the sensor is 3X the linear size (ie. 9X the area), but there are excellent images being produced by even 1/2.7" sensors. Getting away from the dSLR's though, in the usual consumer digicams, larger sensors are generally paired with better lenses, and with more sophisticated cameras. It's not the sensor size or megapixels, but the quality of the sensor PLUS the quality of the lens, and the quality of the camera that all adds together to produce the picture quality.

If you're in the process of picking a camera, I'd recommend that you start bycarefuly decidingwhat you want to do with the camera and how much you want to spend. Chooseseveral cameras that seem to fit; plus or minus a couple of megapixels; ignore sensor size. Read the reviews.Then, look through the sample images available here, also at dpreview and Imaging Resource; see for yourself what each camera can produce. Maybe even print a few - for 20-30 cents each, why not? Make your choice based on the images, rather than the sensor size - it's just not all that important.


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