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...ben Sep 8, 2005 10:03 PM

Does anybody have a sensor size against megapixel chart? I mean a list of sensor sizes showing their respective "effective" output range in megapixel.

Also, does bigger sensor means better? Or sensor quality is stilldependent on the manufacturers.


JimC Sep 9, 2005 12:14 AM

You can't tell that way.

You can find the same sensor size with different resolutions. For example, the Sony 1/1.8" CCD has been available with 3MP, 4MP, 5MP, and now 7MP.

You'll see similar specs with other sensor sizes (more than one resolution avalable in sensors with the same physical size).

Yes, a larger sensor can be better, depending on avarietyoffactors.

The morephotosites (higherresolution) you try to stuff into a sensor, themore light has to hit them for equivalent ISO speed sensitivity (since the photosites for each pixel will need to be smaller in order to fit more of them into a given sensor size).

So,when shooting in low light with a higher resolution (yet smaller) sensor, it canbe like trying to turn up the volume on a weak radio station (only instead of static, hum and hiss, you get image noise).

That's why the larger sensors used in DSLR models have much higher ISO speeds available (even though their resolution in pixels may be lower than some models with much smaller sensors).Larger photosites for each pixel (which means you don't stuff as manyof them into a given sensor size) can gather more light, requiring less amplification of their signal for equivalent ISO speed sensitivity.

Never assume that more megapixels=higherquality. The opposite can often be true.

You really need to take each sensor on a case by case basis (as some advances in sensor technology are being made). Also, there can be a significant difference in image quality, even when comparing cameras using the same sensor (due to metering, lens quality, image processing algorirthms, white balance interpretation which impacts color accuracy, and more).

...ben Sep 9, 2005 1:55 AM

Thanks for your response Jim. It's a big help. :cool:

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