How many megapixels does your camera need?

I was reading the latest iPhone 5 rumours and while most appear to me to be made up, a few are quite likely, such as a beefed up camera. The current iPhone 5 has an 8 megapixel  camera and the iPhone 5S is rumoured to have a 12 megapixel camera. This seems likely because camera upgrades come along every couple of years. It would also then be on a par with the brand new Samsung Galaxy S4, which has a 13 megapixel camera. The question is, do we need all these pixels in a phone camera? Are more pixels better?

The truth is that more pixels do not always produce better photographs. If a camera takes blurred out of focus images because it has a poor lens, then increasing the number of pixels will simply allow it to capture more blurred out of focus pixels. If photos are too dark, then increasing the number of pixels just produces a larger image that is too dark. The same goes for colour casts and other problems that can occur when taking photographs.

The problem is that megapixels are easy for people to understand and for companies to sell. It is a quantity that can be measured and compared from one camera to another. If one camera has an 8 megapixel sensor and another has a 12 megapixel sensor for example, then the larger one is obviously better to much of the general public.

It is easy to convince people to buy more megapixels. It is not easy to convince people that a camera takes better photos. Suppose the next iPhone has an 8 megapixel camera, the same as the current one, but it takes better photos. It is much harder to convince people that it is better than simply saying it has more megapixels. You can't put a figure on a better photo, you can't measure it and you can't compare specifications.

If you try a lot of phones or digital cameras you will soon see that lots of pixels doesn't always produce better photos. It's hard to describe, but it's just the way the image is focused, the colour balance, the lighting and so on. Sometimes cameras with fewer pixels take better photos than those with more pixels.

How many megapixels do you need? The Samsung Galaxy S4 with its massive 5in screen is 1920 x 1080 pixels. That's 2,073,600 pixels or 2 megapixels. Why have a 13 megapixel camera because photos are simply shrunk down to 2 megapixels when displayed on the screen? Even if you display your photos on your big screen HD TV, it is still only 1920 x 1080 pixels - 2 megapixels. Perhaps you like to share photos on Facebook, well, they still only display on your computer monitor or laptop screen and it's probably not much more than 2 megapixels. The iPad 4 with its retina display is actually just 3.1 megapixels.

Suppose you want to print the photos. An A4 sheet is 11.4 x 8.3 inches and the best human eye can detect no more than 300 dots per inch, even at very close range. That's 3420 x 2490 pixels, which is 8.5 megapixels assuming you print edge to edge without any borders at the very limits of human vision. Why then does the Samsung Galaxy S4 have a 13 megapixela camera and why will the iPhone 5S have a 12 megapixel camera? Of course, some people might want to print bigger pictures, but people rarely print pictures these days never mind print bigger than A4. And for those that do, it's probably better to get a real digital camera than use a phone camera. They take better quality photos that withstand enlargement.

The bottom line is, any camera over 5 megapixels is sufficient for most uses and it is better to focus on camera features and quality rather than the number of megapixels.