The Megapixel Race Over? Hardly.

February 9, 2010

David Pogue, who writes about technology and gadgets for the New York Times, has spent years mocking the delusion that megapixels define the quality of a camera.

For example, he once ran a demonstration showing that random viewers couldn’t see much difference in a row of enormous, 16 x 24″ prints, even when the pixel counts varied wildly.

But Pogue made an odd aside last week, at the conclusion of his compact-camera buyer’s guide:

“As the ridiculous megapixel race winds down at last, …”

…a comment which left me scratching my head in confusion.

Perhaps he’s been busy—avalanched under press releases for all those new tablet e-readers. Or maybe he’s aggravated that the megapixel race didn’t stop at 7 Mp, as he hoped in 2006?

Believe me, I understand the frustration; the desire to throw up your hands, declare victory, and retreat.

But in reality, the megapixel war still rages—most obviously among point & shoot cameras. (And it’s the buyers of these mass-market models who are most likely to take advice from newspaper articles, rather than from some specialist geek website.)

Imaging Resource 12-14.9 Mp Digicams

Imaging Resource Breaks it Down

Among current point & shoots, I see a sickening 40 different compacts trumpeting 14 megapixel sensors. And new models are being introduced every day.

With the teensy sensors used in these cameras, diffraction, lens aberrations and noise make such ridiculous pixel counts meaningless—fraudulent, in fact.

Now, Pogue begins his compact-model roundup by noting some limitations inherent to all small cameras: shutter lag, grain, and blown highlights. But he hasn’t much followed his own oft-stated advice: Choose a camera based on its sensor size, not pixel count.

Seven of Pogue’s nine selections have pixels smaller than 1.54 microns. (The Nikon’s are a ludicrous 1.43 microns.) His Panasonic pick does a smidge better, at 1.56 µm.

But compare these to the 2.0 microns of the (still fairly compact) Canon S90—each of its pixels can collect about 70% more light.

His one choice I might grudgingly accept is the 10 Mp Fujifilm F70EXR. Besides having 1.77 micron pixels, this model offers a special low-light mode. Ironically, it works by pairing up pixels, turning it into a 5 megapixel camera! Hey, it’s a Pyrrhic victory, but I’ll take it.

But Pogue’s other picks simply have pixels that are too small, by any reasonable criterion.

I do admit that anyone forced to buy a compact digicam today—lets say your old one just died, and you’re leaving on a trip tomorrow—faces very limited choices.

If need be, you might hunt for a model using one of the new generation of 10 Mp back-illuminated CMOS sensors. For example, Sony’s “Exmor R” chip (versus the regular, non-R kind) works some special tricks to wring the most out of its 1.7 micron pixels.

Meanwhile, even among serious DSLRs, megapixel marketing creeps onwards too. Canon just introduced its Rebel T2i (550D outside the US), with an 18 megapixel sensor.

Canon Rebel T2i

The Amazing Shrinking Pixel Goes DSLR

This is actually rather worrying. Aren’t “enthusiast” photographers supposed to know better? That smaller pixels compromise other aspects of performance, like dynamic range and noise?

Stuffing 18 million pixels into the same 22.3 x 14.9mm sensor area makes each pixel 4.3 microns wide. This is the same pixel pitch that causes Micro Four Thirds cameras to struggle with noise when pushed up to ISO 800.

Consider the 12 Mp Pentax K-x, praised for its high-ISO performance. It uses 5.5 micron pixels instead. This gives each pixel 63% more light-gathering area.

Also remember that on the T2i’s sensor, each millimeter of sensor width contains 232 pixels.

But it is very rare for a real-world lens to resolve detail at that scale with reasonable contrast. If one can do so, it will only be at a single, optimum, middle f/stop. That’s not especially practical.

(Aberrations limit sharpness at wide f/stops; diffraction creates blur at smaller ones—in APS-C cameras, typically f/8 or smaller. For a more technical discussion, start here.)

I wish we could say that megapixel marketing madness had finally ended.

But I’m not seeing any evidence this is true.


9 Responses to “The Megapixel Race Over? Hardly.”

  1. Huggie Says:

    I was wondering when the MP hype was getting to the DSLRs. I don’t feel too bad using my old Dimage A2 😀 .

  2. petavoxel Says:

    A reader asked a reasonable question,

    “You praise the Canon S90 for its 2 micron pixels….. then say

    Stuffing 18 million pixels into the same 22.3 x 14.9mm sensor area makes each pixel 4.3 microns wide.

    Which (to me) implies that the 550D can gather more light per pixel than the S90?

    Am I missing something?”

    Yes, the difference is simply camera size. I should have made that explicit.

    I did write about the S90’s limitations here:

    But I admit, we all have a need for pocketable cameras, sometimes anyway. And in order to shrink down a zoom lens’s length & diameter, you must shrink its focal length—i.e. it will produce a smaller image, implying a smaller sensor.

    You can build a small camera with a non-zoom lens which has a full APS-C sensor (e.g. the Leica X1 or Sigma DP2). But those are quirky exceptions, which haven’t found many buyers.

    In a full–sized camera there really isn’t any excuse.

    Micro Four Thirds teeters right on the edge. It’s obviously trying to find some size/performance compromise; but I think it would have been wiser to hold those cameras back to 10 Mp.

  3. Jax184 Says:

    The T2i has a few genuine improvements over the T1i, but they’re almost all to do with the video mode. And the frustrating part is that outside of the microphone port they all could have been added with a firmware update. Instead Canon expects people like me who want to actually USE the video mode to sell their T1is (I’ve only had mine for 3 months!) and buy an entirely new camera that probably doesn’t take better pictures. I’d expect better treatment for $1000.

  4. alex-virt Says:

    Not all 14 Mp compacts are equally useless. There are a few with better lenses, advanced processing (and premium price tags!) that can do better. Canon G10, for example.

    In 2008, I compared my old G5 (5 Mp) with the newer A720 (8 Mp) and couldn’t find any difference in resolution, but the G10 is a definite improvement.

    However, I keep 14 MP images for printing only. For screen viewing, I downsample them to 5 Mp using bicubic sharper and some tonal adjustments. Resulting pictures look much sharper, cleaner and nicer than G5’s.

    My other camera is Sigma DS14 which is “only” 4.6 Mp, but the image quality is so good that I don’t care for Bayer cameras anymore.

    I think 5-6 GOOD megapixels are what amateurs really need, but ironically, quality sometimes can be achieved only through quantity 🙂

  5. petavoxel Says:

    As of March 25th Pogue is still proclaiming the megapixel race over. If he keeps saying it enough times, maybe it will become true.

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