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The myth of the megapixel

Face of man turning into pixels

Each new wave of digital cameras hitting the shelves seem to up the megapixel arms race. But excessive resolutions don’t necessarily make better photos – so why isn’t this message being passed on to consumers?

Only a few of years back, a 8Mp resolution on a compact digital camera would be considered state of the art. These days, you’ll find it on a bargain-bucket model.

You can now buy 14Mp compact digital cameras far and wide. But what do you actually get out of such high resolutions? Strictly speaking, not a lot.

The most obvious benefit of high resolution is that it allows the camera to record more detail in each shot. This is advantageous if you’re printing enlargements, or if you do lots of digital cropping and editing.

But if you’re not blowing your shots up to poster sizes, there’s little need for such a high res. For a standard 6×4 inch print, all you need is 2.2Mp of resolution. For a larger 10×8 inch print, 7.2Mp is perfectly sufficient.

Loss of picture quality

There’s a further argument against the need for such high resolutions – our extensive lab testing has confirmed that high megapixel image sensors often deliver poorer shots in challenging low light conditions. You’re often left with unattractive, grainy results.

To understand why, it’s worth considering how digital pixels actually work. A 14Mp image sensor has 14 million pixels crammed onto it – crudely speaking, exposing each of these pixels to light collectively creates the photo.

But the image sensors in compact cameras are tiny, and they don’t have a lot of space to host all these pixels. By crowding too many pixels onto a tiny sensor you end up preventing each individual sensor from working as well as it can – particularly in dim light conditions.

Think of an image sensor like a flower patch. If you plant too many flowers on it, too closely together, they block each other’s exposure to the sun, and none of them grow as healthily as they would do spaced further apart.

It’s no different for image sensors. In strong light, a 14Mp compact camera sensor does just fine. But when you’re shooting in low light, the overcrowded pixels struggle to make anything out, and you end up with grainy images that lack satisfying detail.

Ultimately, image quality is more a question of sensor size than anything else. No matter how many megapixels you cram onto a tiny compact image sensor, it’ll never match the performance of a large DSLR sensor in dim conditions.

Reducing megapixel counts

What’s interesting is that Canon, Nikon and Samsung have all climbed down in the megapixel arms race with their top-of-the-line premium compact models. The Canon Powershot G11, Nikon Coolpix P7000, and Samsung EX1 all boast restrained resolutions of 10Mp, in a bid to get the best possible shots in low light.

The Canon G11 and Nikon P7000 each replaced older models which had higher resolutions of around 14Mp, so it seems that manufacturers are aware that the most demanding photographers aren’t convinced by the merits of high megapixel counts.

But shouldn’t this message be spread to all potential camera buyers? Have you ever felt misled by camera adverts or salespeople, and ended up paying more for a high megapixel count you may not have needed in the first place?

Comments
Guest

I have a Sony DSC-HX1, which is 9MP, and it takes absolutely stunning photos – even in low light with no flash.

Guest

it doesn’t mean it is because of its high megapixel resolution but the optical part and then the electronic part. it would probably get you same stunning photos even if you set the resolution down to 2megapixel. try it.

Guest
Photo-man says:
13 September 2010

I agree about the pointlessness of high megapixel counts. I am very demanding of image quality; I shoot with a DSLR the majority of the time, but also have a Fujifilm compact with 6 MP – so much better than the current crop of high MP cameras in low light conditions. And think about this – the majority of your family shots / portraits / social groups are not in outdoors blazing sunlight but in the evening / indoors, so low light performance is key. Also, subdued light (including overcast daylight) is so much better for portraits than harsh bright sunlight (which causes dark shadows in all the wrong places!) – so again, you want a camera for this, not the sunny days (which they’ll all do anyway).

Guest

I have a FujiFilm F100FD with 12M pixels, I think that it is actually worse than the FujiFilm F40FD with 8M pixel that I had before. With non optimal light the F100FD will smear the image with grainy “made up” pixels.

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Guest

Hi Rif – that’s an all-too-familiar story, I’m afraid. A good friend of mine “updated” her much-loved 6Mp superzoom camera with a newer 12Mp version (similar in most regards), and she was telling me how underwhelmed she was by her new camera’s picture quality, and how much she regrets giving away the old one. What’s sad is she now thinks she takes fewer photos than she would have done with her old camera

Guest
TElestrobbist says:
14 September 2010

Pixel density is pretty much the key, this article is pretty good
sphoto.com/techinfo/dslrsensors/dslrsensors.htm

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Guest

We’re talking about this on the Which? Technology podcast, live on Thursday. My guess is that sales and marketing people tell unwitting potential buyers: “Never mind the quality, count the pixels.”

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Guest

…but is there a reliable – and comprehensible – way of measuring sensors?

Guest
Edward says:
14 September 2010

I too agree that high megapixel cameras are unnecessary. I have a Canon 4mp camera and have produced 55 X 36 cm. enlargements perfectly well with no sign of pixelation and plenty of detail.
As usual the manufacturer sets out to trick us into buying the next model.

Guest

There are often benefits to more pixels (mainly being able to keep a shorted focal length and cropping rather than zooming and risking shake) but I have always agreed with and raised the points above. What I find most annoying is that people screaming about their sensor size have not thought about the type of sensor being used, the processing chips inside the camera, or most importantly the quality of the lens on the camera, it’s maximum aperture etc. Luckily I think this is becomming less of an issue as digi cams become more common. I also love it when a camera is defined as ‘takes High Definition pictures’ – I should hope so as ‘true HD’ is only around 2Mp 😀

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Guest

But it depends on what you want to do with the pictures. I use a Sony Alpha A700 with 14megapix and I shoot in RAW. So even an 8 Gig memory card gets full fairly quickly. And while you are correct that all those pixels are only useful if you want to print the whole photo poster size – what if I want to print a small piece of it, cropped out of the whole image, A4 size? Then I need those pixels.

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Guest

Hi Peter – you’re absolutely right, of course, that those pixels come in handy when cropping your shots. But keep in mind, the experience of a compact camera with a 14Mp sensor would be wildly different to your experience with a high-res DSLR sensor.

DSLR sensors can better enjoy the luxury of high megapixel counts, as they’re so much larger than compact camera sensors. WIth compact sensors, I can’t help but feel manufacturers are slapping extra megapixels onto them because they CAN, but not because they SHOULD…

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Guest

Better resolution has done away with big zooms. As Peter says, if you want to crop a detail of a pic, then being a member of the multi-mega pixel club is pretty useful. I’ve done away with my SLRs and zooms for a micro four thirds (this is what comes of listening to the podcast regularly – you get gadget-lust) and now I can carry a small but hi res camera wherever I go. I guess it’s all about getting the right advice when you buy.

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Guest

Keep in mind Nick, despite being smaller than DSLR cameras, micro-four-thirds (MFT) cameras have image sensors around 8 times larger than you’ll find on a compact. So the high resolution on MFT sensors is more usable, and MFT cameras can still take good low light pics

With compact models, I’d hesitate to suggest that digitally cropping in the post-edit gives you the same quality results as zooming at the point of taking the photo itself. This is especially true in dim conditions.

Guest

If the size of the sensor is the problem, is there any reason – apart from cost – why the larger sensors used in DSLR cameras cannot be fitted to digital compacts?

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Guest

Hi Len – cost is an issue, but it’s more a matter of the physics of the lens-to-sensor relationship. It wouldn’t be possible to combine a large DSLR-equivalent sensor with a small compact-camera lens.

However, we’re seeing now some exciting mirrorless system cameras that are remarkably smaller than a DSLR, but with equivalent sensor sizes – the Panasonic GF1, the Samsung NX100, the Sony NEX-5 and NEX-3 – these have interchangeable lenses which are smaller than DSLR lenses, though larger than compact camera lenses

Guest

I’m not a prolific photographer, so don’t spend much time reading up on the latest photo gear/technology. The megapixel escalation was evident to me, but I couldn’t see any rationale for it. This article and discussion thread has been great – concise, encapsulated knowledge/opinion from people with the right experience. Thanks.

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Guest

Sony’s just unveiled it’s 16 megapixel sensor for…mobile phones. Tut tut. Is that really needed? I think not. http://gizmo.do/dtYHSt

Guest

This is one of the most irritating.I have been trying to explain (in simplest form at http://camera2012.blogspot.com ) that megapixel is nothing but just pure myth. High megapixel is useful but not for an average user not even for a semi-professional. By putting all the efforts on higher resolution, the optical part has been considerably neglected or had to be compromised to the cost. So overall performance has been compromised. Somehow the message just doesn’t get through, and people just follow the mega pixel race. My best digital camera is 2megapixel and it is 10 years old, and i am loving it.

Guest

Public lack of knowledge has been hijacked by some greedy manufactures and no matter what, as long as it has a high megapixel, its market is guaranteed. and in meantime some manufacturer went even further to neglect the optical/lens which is the most important part of a camera. and people just keep buying it. then again maybe that people deserve not better than those ****** cameras.

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Guest

I usually use a Nikon DSLR for first class photographs and enlargements – I use the viewfinder to compose the shot in all conditions. So in general the cropping is really minimal unless I get say an “accidental” superb expression on a face – so I don’t waste pixels – These shots enlarge to 10 x 8 without a flaw and – all customers are really satisfied. So much so they usually ask for several copies.

The trouble is with the lack of viewfinders on newer digital compacts coupled with the low quality display in bright sunlight – there is a need to “point and hope” now rather than “compose and shoot” needing to crop massively to obtain a decent photograph – so high Megapixels are needed.for those who normally don’t know how to take proper photograph! 🙂