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Old Oct 28, 2006, 8:23 PM   #1
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Im not a Pro at all, and im thinking of getting a DSLR and still really confused....what's the main difference between the 6MP 8MP and 10MP except for the enlargment of pics?and what's the max i can get with each?
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Old Oct 28, 2006, 9:31 PM   #2
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Assuming the same size sensor in the camera, more megapixels means smaller photosites which means more noise and less dynamic range. Some of these drawbacks can be controlled with more agressive noise reduction however this results in lost detail. There is an optimal number of megapixels for each size of sensor to get the best results.

As for print size, Peter iNova spells out how many megapixels you need: http://www.digitalsecrets.net/secrets/Frames.html
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Old Oct 29, 2006, 5:12 AM   #3
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Quote:

Assuming the same size sensor in the camera, more megapixels means smaller photosites which means more noise and less dynamic range. Some of these drawbacks can be controlled with more agressive noise reduction however this results in lost detail. There is an optimal number of megapixels for each size of sensor to get the best results.

I actually agree with that! :-)(It is very true)

I think it gets rather complex though...

Larger photo-detectors also permits you to be able to use smaller apertures before the light raysdiffraction limits occur. (Smaller photo-detectors will start to lose details more quickly as you turn down the aperture - as the diffraction limits occur beyond its pixel size) So more mega-pixels does not mean more resolution, unless you really increase the image sensor's physical dimension.

It is also true about dynamic range: The larger photo-detectors can afford to contain more photons before overflowing. On the other hand, a smaller photo-detector will overflow quickly, and as a result, "Blown out highlights" - "Lost of details". Photons also tend to miss smaller photo-detectors, so unless if the micro-lens arrays are well done, the signal to noise ratio will be lower. (And that will result in more noise andless image details - as less photons have managed to reach the smallerpixels - & at the same time noise from the electronics swarming in to obscure image details)

Maybe the last thing is; larger photo-detectors are also more sensitive to light rays, so they can afford to have higher ISO performance. (Some image sensorscango all the way up to ISO 1600 without loosing much image details)

The best thing for pixel-peepers is for themhave an image sensor with larger photo-detectors. :-)Because no matter what, the signals thatthe larger photo-detectorswould be receiving will always be greater than it's totalnoise output; &as a result, "More signal,less noise". That is the reason why ultra compacts have such poor ISO performance,the tiny photo-detectors of their minuscule CCD(s) are an extreme example of "More noise, and less signal...".

Sometimes, the law of physics just cannot be overlooked. (After all, we are all governed by it; everyday)


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Old Oct 29, 2006, 9:44 AM   #4
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Mazen,

The link by Bob is useful. But let me say this: megapixels should really be one of the very last points to consider when buying a DSLR. It is absolutely one of the least useful aspects for 99% of photographers. There are so many more important things to consider that will have more of an impact on your photographs.

Don't get caught up in the marketing hype of MPs and don't drown yourself in techno-babble. Look at other camera features and lens features and DSLR systems and make your decisions based on those other factors. If you do that, it won't matter if the camera you select has 6, 8 or 10mp.

Good luck!
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