What the Hell is a Megapixel?

The techno-jargon you encounter when buying a digital camera can be confusing and in many cases can result in spending hard earned money on a camera that doesn't do what you want. As more and more cameras enter the market so the jargon increases as does the confusion. In many cases people buy cameras on the advice of friends or relatives, who themselves may have very little knowledge of photography. This is not the ideal way to purchase your first camera.

I have tried to put together a jargon free technical guide for anyone intending to buy a new digital camera. This is my attempt to explode some of the myths and sales babble you will encounter in your search for your first digital camera, I hope it helps. Probably the most confusing aspect of digital photography is the megapixel rating and how it can affect the quality of the finished image. It also affects the price of the camera and this is where the expensive mistakes are made.

So What is a Megapixel? The short answer is, a megapixel is one million pixels. When camera manufacturers talk about their cameras producing X megapixels they are multiplying the length of their best quality image by the width (in pixels). So a camera producing an image 1,000 x 1,000 will be said to produce 1 megapixel, easy enough, or is it? OK then, so re-wind a little, what is a pixel?

Digital images are constructed of dots, or to be more precise, blocks, called pixels. The first image you see below is of the front of a boat. The highlighted part looks like a blue background with a yellow or gold scroll design. The second image is a 1600 times enlargement of a section of the scroll and background. Each square block you see is one pixel.

The common fallacy among digital camera owners is "a megapixel is a megapixel" WRONG! Megapixels can vary in size depending the technology used in the manufacture of the camera's sensor. Some technology is capable of creating smaller or sharper pixels than others. Therefore a one camera producing 3 megapixels may well be better than another with the same rating.

A medium format camera such as the Hasselblad, (In my humble opinion one of the best conventional cameras ever made) on film, would produce a negative 6cm x 6cm. A digital back for such a camera costs in the region £10,500 (no I haven't added too many zeros!) It is capable of producing a print 30" x 40" and you would be hard pressed to tell the difference between it and a conventional print from film stock. However, the resolution is about 6.5 megapixels, less than some cameras costing around £1000. I am also informed that one of the cameras sending pictures back from Mars is only 1 megapixel.

So when you are choosing a new digital camera and you are told that the nipoflex 4000 super deluxe is better than the 3000 standard, because it produces more megapixels for your money, just remember that the only test of the quality of the final print is to see one hanging on your wall.

Perhaps it is also important to bear in mind, what you want to do with your pictures once you have recorded them on your camera. Would you buy a car capable of producing enough brake horse power to pull a tank behind, if all you want to do is drive granny to the shops once a week? Most photographs don't leave the computer so what is the point of having an image 20" wide if you can only view it at 6" wide?

It should also be noted that the human eye can not discriminate detail below a certain level. Although this varies between individuals, it is generally accepted that 200 dots per inch is the limit. Anything above this would be seen as a continuous tone, in fact images on a computer are normally set at 72 pix per inch. Every magazine or newspaper image you see is made up of dots, and has been that way for nearly 200 years, long before even the word "digital" was invented.

I hope I haven't left you even more confused than you were before you started to read. There are other important things to look for in a digital camera but the amount of megapixels should not be your first priority. The quality of the lens should be one of the first but it is difficult to see that without looking at the image the camera can produce.......... ask to see examples.

If you need further help why not join our forum and ask..............