It's not the megapixels that matter, but the surface area.
Even a cropped-sensor DSLR can have a sensor 6-8 times the area of a compact or bridge camera. The 24x36mm full frame sensor is even larger.
The problem with increasing megapixel count is that you have to squeeze more and more pixels onto a sensor which remains the same size, surely I don't have to draw you a picture to explain the inherent problems.
The typical cell phone uses a 1/6" sensor, which has a 4 sq mm surface area. The iPhone 5 uses a 1/3.2" sensor, which has a 15 sq in surface area.
Lower end compact cameras, as well as most bridge cameras use a 1/2.5" sensor. The huge zoom lenses on bridge cameras require a smaller sensor or their lenses would be an unmanageable size. The surface area of these sensors are 25 sq mm.
Medium quality compact cameras have 1/2.3" sensors, which are 28 sq mm.
High end compact cameras (Canon G15, Nikon P7700, etc) use 1/1.7" sensors, which are 43 sq mm.
The Nokia Lumina 2010 uses a 2/3" sensor, having 58 sq mm.
Nikon 1 and the Sony RX100 use a 1" sensor, with a 116 sq mm surface area.
Micro 4/3rds cameras use a 2" sensor, having a 223 sq mm surface area.
Canon cropped DSLRs use a 1.6x crop sensor, with a 329 sq mm surface area.
Nikon, Sony, and Pentax DSLRs have a 1.5x crop sensor, with a 370 sq mm surface area.
Sony NEX cameras also have a 370 sq mm surface area.
Full frame DSLRs have a 864 sq mm surface area.
The Nokia's 41 megapixel sensor is pure horse hockey.
It does indeed have 41megapixels worth of photo diodes, but they are too small to create a photo. A technique called "Binning" is required to bunch enough of the photodiodes together to get a useable photo.
The result of binning is an effective sensor of around a 5~8megapixels.
It depends which cameras you are comparing and how you are performing the measurement - by actual inches (rather, fractions of an inch) or millimeters or by megapixel count. And, under certain comparisons, the "compact camera" imaging sensor can be larger than the dSLRs... for example, the the Nokia 1020 has a 41 megapixel imaging sensor. There is no other camera (compact, dSLR or otherwise) with that high of a megapixel count.
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The chart in the link graphically compares the sizes.
http://en.wikipedia.org/wiki/File:Sensor_sizes_ove...
It's not the megapixels that matter, but the surface area.
Even a cropped-sensor DSLR can have a sensor 6-8 times the area of a compact or bridge camera. The 24x36mm full frame sensor is even larger.
The problem with increasing megapixel count is that you have to squeeze more and more pixels onto a sensor which remains the same size, surely I don't have to draw you a picture to explain the inherent problems.
The typical cell phone uses a 1/6" sensor, which has a 4 sq mm surface area. The iPhone 5 uses a 1/3.2" sensor, which has a 15 sq in surface area.
Lower end compact cameras, as well as most bridge cameras use a 1/2.5" sensor. The huge zoom lenses on bridge cameras require a smaller sensor or their lenses would be an unmanageable size. The surface area of these sensors are 25 sq mm.
Medium quality compact cameras have 1/2.3" sensors, which are 28 sq mm.
High end compact cameras (Canon G15, Nikon P7700, etc) use 1/1.7" sensors, which are 43 sq mm.
The Nokia Lumina 2010 uses a 2/3" sensor, having 58 sq mm.
Nikon 1 and the Sony RX100 use a 1" sensor, with a 116 sq mm surface area.
Micro 4/3rds cameras use a 2" sensor, having a 223 sq mm surface area.
Canon cropped DSLRs use a 1.6x crop sensor, with a 329 sq mm surface area.
Nikon, Sony, and Pentax DSLRs have a 1.5x crop sensor, with a 370 sq mm surface area.
Sony NEX cameras also have a 370 sq mm surface area.
Full frame DSLRs have a 864 sq mm surface area.
The Nokia's 41 megapixel sensor is pure horse hockey.
It does indeed have 41megapixels worth of photo diodes, but they are too small to create a photo. A technique called "Binning" is required to bunch enough of the photodiodes together to get a useable photo.
The result of binning is an effective sensor of around a 5~8megapixels.
Pure sleazy marketing techniques.
Here is an article and chart showing the various sensor sizes.
http://dondavisphotography.blogspot.com/2011/12/se...
BTW there are at least three DSLR sensor sizes, and about a half dozen compact sensor sizes.
It depends which cameras you are comparing and how you are performing the measurement - by actual inches (rather, fractions of an inch) or millimeters or by megapixel count. And, under certain comparisons, the "compact camera" imaging sensor can be larger than the dSLRs... for example, the the Nokia 1020 has a 41 megapixel imaging sensor. There is no other camera (compact, dSLR or otherwise) with that high of a megapixel count.