Size does matter

As an architectural photographer I am often out in public places taking photographs. Because I use a rolling camera case and always shoot with my camera on a tripod, I am often approached by amateur photographers with questions about what I’m shooting and what equipment I use. The one question that I am always asked is “How many megapixels?” 

One point that many amateur photographers are unaware of is the difference between megapixels and sensor size and how this relates to image quality. Many people mistakenly assume that all 12-megapixel cameras are equal; that a 12-megapixel point & shoot camera will produce photographs with image quality as good as a 12-megapixel DSLR. This is not true.

While the number of megapixels is important in producing a high-resolution image sensor, the actual size of the individual photosites is a very important factor in determining the image quality produced by an image sensor. 

Photosites are the individual light sensors that together make up the image sensor. The number of individual photosites equals the megapixel size of the sensor. A 12-megapixel sensor has 12 million photosites. Now if that 12-megapixel camera is a point & shoot camera it probably has what is called a 1/2.3 format sensor. This sensor is approximately 6mm x 4.6mm. That’s an area of 27.6 square millimeters. The Nikon D3 has a 12 Megapixel FX format sensor that measures approximately 36mm x 24mm. That’s  864 square millimeters for the FX sensor! That's more than 30 times the size of the 12-megapixel point & shoot.

Sure, there’re both 12-megapixels, but the point & shoot camera has individual photosites that are much, much smaller than the photosites of the DSLR with the FX sensor. This is important because larger photosites have more light gathering ability and produce images that have better color and less noise. This is one of the reasons that the Nikon D3 produces images with such remarkably low noise. 12 megapixels is actually a low pixel count for such a large sensor, but the individual photosites are very large. It’s these large photosites that allow the sensor to produce such clean, noise free images.

This is why an 8 megapixel DSLR will produce better image quality than a 12-megapixel point & shoot. Larger photosites produce better image quality. There are of course other factors such as the cameras image processor and lens quality, which again is almost always better in a DSLR.

 So keep this is in mind when you’re shopping for your next digital camera. A pocketsize point & shoot camera may be exactly what you need. But just because it’s a 12-megapixel camera does not mean that it will produce images as good as that 12-megapixel DSLR that you really want! Size does matter.

Posted by Curt Clayton at 3/24/2009 10:57 AM
Categories: Digital cameras, Digital Photography
Tags: DLSR megapixels digital photography digital sensors digital cameras
 

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