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Megapixel Myths

01 Sep Posted by Mark in Guides |

How many megapixels do you need on your camera? Does that extra 4mp make that new camera you’re looking at a good purchase? Obviously, more is better, isn’t it? Well, it turns out that isn’t always the case…

Pixellated Girl - photo from Digital Camera

Do you need more megapixels?

My first digital camera had 2.1mp. For a compact at the time that was a pretty good spec, but by today’s standards many people would say it must be useless. But it isn’t – my mother still uses that camera on holiday to this day, and despite me pushing her to upgrade she always declines. She thinks the photos she prints are fine – and she’s right. She prints 6×4 holiday snaps, and they look as good as the ones taken on her old 35mm compact that she eventually moved away from as it got harder to get her films processed.

So, what is a megapixel? It’s a measure of how many pixels, or ‘dots’ a picture taken by a digital camera is made of. Think of the picture you take being projected onto a grid, where each square changes colour based on the light that lands on it. Smaller boxes makes for a more detailed picture, and the smaller the boxes the more you need to make up the picture. So, more megapixels means more dots, and in theory more detailed pictures. A megapixel = one million pixels – roughly the number on a HD television.

So if 2.1mp works, why do modern digital compact and digital SLR cameras have more? Well, up to a point more is better. If you want to blow your photos up to A3 size then 2.1mp will be a bit below par, but not by as much as you might think. David Pogue from the New York Times tried this out with slightly higher pixel counts and found that almost no-one could tell the difference between a 5mp and 13mp picture blown up to poster size. Some of the earliest professional DSLRs used for photoshoots and the like had a lowly (by modern standards) 5mp. Don’t get me wrong – I’m not saying you want a 2.1mp camera these days, but for anyone outside the professional sphere anything above 6mp on a camera is going to make very little difference to their photos. In fact in certain circumstances more megapixels can be a disadvantage…

Take my Fujifilm F80EXR. This camera has 12mp, and replaced the older F70EXR which had 10mp. These cameras are known for their good low light ability (for a compact camera at least) due to some clever stuff they do with their sensor. However, what’s important for us here is that in these conditions the F70 produces better pictures than the F80 by some peoples reckoning. Why? Because to fit those extra 2mp worth of dots onto the camera’s sensor without making it bigger, each dot had to get a bit smaller and so picks up a bit less light than the bigger dots on the F70. This means that the F80 produces noisier pictures than the F70 even though Fuji obviously intended it to be an upgrade. (Don’t get me wrong, the F80EXR is still a great camera and has other advantages over the F70 in spite of this!)

For Digital SLRs the picture is a bit less clear as they have larger sensors, and are much more dependent on the attached optics. But there is still little advantage to most users in ramping up the number of megapixels. An 8mp camera with good optics and user skill will still turn out great, high quality pictures, whilst a 14mp camera with a bad lens, used poorly, will not look half as good.

In the end, cameras today will probably all have at least 8mp, and probably more, and this normally isn’t a problem. But when you’re buying or comparing cameras, don’t get dragged into comparing the number of megapixels – it is one of the least relevent things to think about, and don’t be afraid to pick a camera with a smaller number if you feel it suits you better in other areas.

 

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