The Great Megapixel Scam

After seeing camera after camera continually released by the major (and countless minor) camera makers, each touting more megapixels than the last, it’s time to help get some basic facts out to the camera-buying public:

More is not necessarily better.

That probably seems counter-intuitive to a lot of people. On the surface, it would seem obvious that given the choice of a 6-megapixel camera and a 10-megapixel camera, the 10-megapixel camera would be superior, and the better value. But that’s often not the case.

Let’s forget about the bogus and deceptive “effective megapixel” ploy used by many no-name digital camera makers. They take a lower resolution sensor (say, 4 megapixels), and digitally enlarge the image – in-camera – to a higher resolution (say, 7 megapixels), and advertise the camera as a 7-megapixel camera. You’re really only getting 4-megapixel quality, and even that quality is dependent upon the lens quality, the in-camera imager circuitry, etc. So let’s skip those and talk about true image resolution.

Say you’re comparing two current models of compact digital cameras from a reputable camera maker (Olympus, Nikon, Canon, Pentax, Kodak). We’ll assume they have decent quality lenses and imaging circuitry. One is a 6-megapixel model, and one is a 10-megapixel model. Which is going to give you the best image quality? All other things being equal, it’s very possible that the 6-megapixel model will give you better images.

Here’s why…

A digital photo is made up of lots of pixels (an abbreviation for “picture elements”). Pixels are lined up in columns and rows across the image sensor. The average image sensor (the part of the camera that collects the light – that holds the pixels) for a compact digital camera is about 3/8 of an inch across – significantly smaller than a postage stamp. The megapixel count refers to how many millions of pixels are squeezed onto the sensor – 6 megapixels equals approximately 6 million pixels.

So here’s the deal: When it comes to pixels, size matters. And not just the size of the pixel, but the space between pixels matters too. Each pixel collects light and determines colors. The bigger the pixel, the more information each pixel can collect. What’s more, each pixel sends the information it collects to the camera’s processing chip via an electrical current. The more pixels are crammed onto a sensor, the hotter the sensor becomes, creating image noise (a kind of grainy or dirty appearance to the images, especially noticeable on indoor and low-light shots).

If camera makers increased the size of the sensor as they added more pixels, then a higher megapixel camera would probably be the better choice. But what camera makers tend to do is simply cram more pixels onto the same size sensor, and then rely on noise reduction software inside the camera to keep the noise down. But in reducing noise, the noise reduction process also reduces image detail. You may not notice the loss of detail on a 4×6 print, but it may become very noticeable on a 5×7 or 8×10 – the photo just doesn’t look “sharp”.

Thankfully, camera makers seem to have slowed in their race for more megapixels.

In all honesty, 5 megapixels is generally plenty to get a good quality print up to 8×10 size, unless you do MAJOR cropping of the image. So unless you plan to print poster-size images (in which case you should use a digital SLR, which has a larger sensor size to start with), don’t get caught up in the megapixel hype.

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