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Old Sep 10, 2002, 2:57 PM   #1
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Default Pixel vs. Pixel

O.K. I'm looking to upgrade to a camera with more pixels. Currently I am using a 2 megapixel camera. There seem to be several 5 megapixel cameras out there, so I just buy the one that I want? Not so. I read in another source that not all pixels are the same. In fact they point to the Sony 717 and say it has small pixels and an older Cannon with only 3 megapixels has larger pixels and a better picture. What gives?
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Old Sep 10, 2002, 4:51 PM   #2
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They are apparently referring to the physical size of the CCD. Larger CCDs have larger photosites which correspond to pixels. Larger photosites with corresponding larger lenses and physical aperture sizes for the same angle of view capture more photons than smaller photosites for the same exposure. This improves signal to noise ratio and allows potential for greater ISO sensitivity. There are other factors but that's one big difference between digicams like the Sony F717/Minolta D7/Nikon 5700 (which all use the same CCD AFAIK) and DLSRs. Unless you're willing to spend DLSR money it should not be a major factor in your choice.

Base your choice on performance and features you really need if you're going to make the jump to a semi-pro camera.
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Old Sep 10, 2002, 6:09 PM   #3
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Default pixels v Pixels

I agree it's all something of a myth. If you've got over 2M and don't need 10X8 prints, it seems to me what matters is ASA sensitivity and that's the chip and the lens for a given resolution, and the processing speed between shots. So low sensitivity is all round bad news. Flash takes more out of the batts, also more auto focus probs in low light, So my feeling is checkout ASA and noise first.
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Old Sep 10, 2002, 8:39 PM   #4
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Padeye, I like your explanation. So basically there are no non DSLR camera's with a larger CCD?
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Old Sep 11, 2002, 2:06 AM   #5
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Padeye..

This may be true but I have neot seen any objective evidence that more space per pixel improves anything.

Th real issue should be objective data .. doe sone camera's lens+chip resolve better than another. I supect in the 5mp range the real differences are in the optix and not the chips.
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Old Sep 11, 2002, 4:37 AM   #6
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Steve, exactly what I was trying to say its largely down to glass and chip and these are the expensive to make (and generally heavy parts). Which is why real pro. cams working in all situations have big heavy lenses and use large film formats! Software options come very cheap.

[Edited on 9-11-2002 by voxmagna]

[Edited on 9-11-2002 by voxmagna]
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Old Sep 11, 2002, 11:56 AM   #7
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AFAIK there are no non-DLSRs with a CCD larger than the 2/3 size.

Vox, the lens can't be separated from the CCD size of course but it all works together.
Say you double the size of the CCD with the same number of pixels. You'll have to double the focal length for the same angle of view. That means the same relative aperture is doubled in diameter meaning four times as much light strikes each photosite for the same EV. With all other things being equal there should be a better signal to noise ratio at a given ISO sensitivity and potential for greater ISO numbers.
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