As digital photography and DSLRs began to replace 35mm film, as well as other film types (anyone remember APS?), the focus started to become, "how many megapixels does it have?" When I was teaching classes, I was asked time and time again, "how many megapixels do I need for a good picture?" Most people failed to realize that the megapixel (MP) rating is just one link in a chain that makes a good image. Sure you have your megapixel rating, but there are other things to consider; CCD vs CMOS, the make of the camera, optics, and even how you print your images out. These all contribute to the quality of the image.
But even when that is all said and done, the question still stands; do megapixels matter? Did you know that the human eye cannot discern the difference of an image over 6MP? Meaning that the average person, if they look at a photograph that is 6MP and then look at that same photograph shot at 10 or 12MP (and I'm talking about the average person), they usually can't tell a difference between the two of them. Now if someone were to look at that same picture in the 1 or 2MP range, the differences become a little more apparent. Also, there is the little-addressed issue that as megapixels increase, the chance for image noise (static distortion of coloring in an image) increases as well. Why? Well first you have to understand that in digital cameras, especially compact point-and-shoot style cameras, the image sensor (whether it is CCD or CMOS) is smaller than a 35mm negative, and the size of the sensor rarely changes. So when you have a small sensor like that, and you jump from 6MP to 12MP you are doubling the amount of light collecting devices but keeping the sensor size the same. The result is a decrease in sensitivity of the camera and an increase in noise because the amount of light collected by a single pixel is smaller. At the same time, increasing the number of pixels is supposed to lead to more details (resolution), but in order to achieve that better lenses with high resolution are needed. However, "better" lenses are bigger and don't fulfill the requirements for "small" cameras any more.
Digital single lens reflection cameras (DSLRs) basically show the same behavior but the sensor of those cameras and the single pixel is much bigger. Therefore, the cameras have higher sensitivities and show less noise. The high quality lenses provide the necessary resolution and the cameras are designed for high pixel counts.
But still, people will tell you that "pros" say you need more megapixels, you need it for better quality images. No one will take you or your work seriously if you don't have massive amounts of megapixels. Well, who are these pros? Are they the ones shooting for National Geographic? Are they shooting for Sports Illustrated? Is their art hanging in a museum? Or are they any one of countless "pro" photographers that have saturated the wedding scene? In 2008, Ken Rockwell (controversial photography critic/reviewer, love him or hate him) stated in The Megapixel Myth that "Sharpness depends more on your photographic skill than the number of megapixels, because most people's sloppy technique or subject motion blurs the image more than the width of a microscopic pixel." He also goes on to tell about 13x19" prints that sold in the Jon Bekman gallery in Manhattan for $650 each. They were made from a 6MP D70. Another person favorite of mine is when asked about 12MP cameras, Canon spokesman Rudy Winston said, "It's overkill."
Even in my personal stock I have images I made from a 2.11MP Olympus C2100 that I would put against any of my 35mm images, or anything that I made with a high resolution digital camera. The C2100 has great optics and this contributes a lot to the quality of image it produces. Now don't get me wrong, as with any other camera, I've shot some really garbage with it as well, but this is usually due to operator error rather than the fault of the camera, or any resolution issues. It is important to note that the CCD sensor in this camera is larger than the sensor installed in most compact cameras - as can be seen this is not a compact camera at all, but more like a mini-DSLR.So why do higher resolution cameras continue to come out and saturate the market? Well, would you buy a new camera every year or two if they were all still 4 or 6MP? Probably not. And the manufacturers know this, so they keep pumping out new models every year with higher resolutions every year. But, do you really need it? When it's all said and done, the choice is yours. When I shoot digital I don't tell people the resolution I'm shooting at because I don't want people to have preconceived notions of what the image is going to be like. The thought process being if I'm shooting high resolution then it's going to be good, if I'm shooting low resolution then obviously it will be trash. Let the images speak for themselves.
