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Old Mar 24, 2006, 5:58 AM   #1
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When people ask me about which camera to buy, I don't usually name a model but tell them that if they just use the camera to get 6x4 prints or to email pictures, then they need no more than 3MP to 4MP..

They often tell me that the people in camera shops (and most of their friends) tell them to by the camera with the most megapixels.

When I suggest that a long zoom will allow you to better frame your subject and avoid wasting pixels, they say "the multi-megapixel image allows you crop the picture to get the same result"

most of them are don't appreciate that when you keep the sensor the same size but make major increases in the number of pixels, you vastly increase the problem of "picture noise"

I obviously impress them with my arguements, as most of them go out and buy a point-and-shoot camera with 6MP - 7MP and a 3x zoom..

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Old Mar 24, 2006, 10:41 AM   #2
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I was confused by the logic put forth. There is an age old rule of thumb that goes like this: ...for the highest photo quality, use your maximum pixel count (the greatest resolution your camera was designed for) and the least compression when storing the photo on the flash memory card...

Unfortunately, what happens is those folks purchase a 6 or 7mp camera and then throttle it back to 3mp or less, with the maximum compression, and they complain that their 6 or 7mp camera takes bad photos. LOL!

Zooming does not affect resolution by the way.

MT (a state university digital camera Instructor)
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Old Mar 26, 2006, 4:21 AM   #3
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Let us assume we have 3 type of zoom lenses - 1x, 3.2x and 10x. Let us assume we have 3 type of sensors (with equal quality per unit area) - 100 MPix, 30 MPix and 3 MPix. Let us assume we install the 1x on 100 MPix, 3.16x on 30 MPix and 10x on 3 MPix.

I would say that those 3 cameras will produce photos with similar quality per unit area. The photo 100 MPix & 1x zoom will catch 100% of the scene. The photo 10 MPix & 3.2x zoom will catch 10% of the scene. The photo 3 MPix & 10x zoom will catch 1% of the scene. The comparison is between the scene crops from the first two cameras which correspond to 100% scene from the 3rd camera.

There are other important photographic issues which I would not discuss in this topic.

The 1st camera today is still not produced. The 2nd one could be produced but because of the dimension of 30 MPix sensor the lense should be very big and very expensive. The 3rd camera I can have in my hands for less than $250.

My conclusion - MPix could never compensate for the lense.

It seems that I have made mistake. The correct number is 300 MPix not 100 MPix
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