 BetterPhoto Member |
Is larger MegaPix necessarily better ? Are there other factors other than the size of a CCD that dictate the quality of final image produced by a digital camera? If so what are they?
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robert G. Fately |
Actually, Lesley, the term "soze of a CCD" is confusing, because there is a difference related to the physical size. Let me explain: All things being equal, more megapixels is better - to a point (which I'll get to). If you have two CCDs that are exactly 1 inch square, and one of them is a 1 megapixel while the other has 4 MP, the latter will have twice the resolution of the former. The first CCD would have 1000 pixels x 1000 pixels; the latter 2000 pixels on a side. The 4MP chip will be simply able to capture more detail. Okay so far? Now, there is a limit here - if you try to cram too many MP on that 1" square, each individual "light well" must end up being so tiny that random heat from the electronics themselves will create reactions that look the same as if light is hitting the pixel. This is referred to as noise. It is for this reason that many folks who moved from a 3 or 4 MP point & shoot camera up to a 6MP P&S do not move up to the latest and greatest 8MP models - cramming 8MP on the relatively small chip leads to noise problems. And THAT gets us to the other 'size' issue - the physical size of the CCD ship itself. Say I have 2 9MP CCDs; one that's 1" square and the other 2" square. Now you can see that while both CCDs have the same 3000x3000 matrix of light wells, the 2" version allows for those wells to be much larger, and thus less noise-prone, than the 1" version. The above chip sizes are examples only; obviously there's not a 2" chip in any camera you'll be buying soon (they do exist, but they cost a lot). But the principles hold. Of course, the CCD is only the first part of the story - the processors that take that data and convert it into a usable picture have a role in how good or bad the image will look when it hits your flash card. But I hope you get the idea at least.
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Justin G. |
Also your glass between you and the image has a lot to do with it. Bad glass affords the opportunity for bad pics. Great glass affords the opportunity for good pics as long as all other parameters are great.
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