Big Sensor a Small Step for Cameras
By DAVID POGUE
Published: July 24, 2008
Every camera manufacturer wants a bigger slice of that $42 billion digital-photography pie. So what do they do? They pile on bells and whistles. Smile recognition, anti-red-eye, blah, blah, blah.
Truly revolutionizing the field really wouldn’t be so complicated, though. All someone would have to do is stick a big sensor into a small camera, and then let the euphoria begin.
See, the camera companies would like you to believe that the megapixel count is the most important measure of a camera, but that’s just not true. Lens quality, circuitry speed, in-camera processing — lots of things are more important.
The best overall predictor of image quality, though, is the size of the sensor inside. Big sensors absorb more light, so you get better color and sharper low-light images. Small sensors pack too many light-absorbing pixels into too little space, so heat builds up, creating digital “noise” (random speckles) in your photos.
For all these years, then, there’s been an inviolable rule: If you wanted a big sensor, you got a big camera — one of those big, black, heavy single-lens reflex models. If you wanted a cute, tiny camera, you were stuck with a cute, tiny sensor, generally about one-tenth the size of an S.L.R.’s.
Clearly, what the world has been waiting for is a pocket camera with a huge sensor. But there are lots of reasons why nobody built one.
First, it would be much more expensive than a typical shirt-pocket camera.
Second, the maker of such a camera would have to start proclaiming sensor size as a critical measurement — thus contradicting all those years of preaching the importance of megapixels.
Third, the big camera makers might think twice about selling a compact camera that can take S.L.R.-like photos. What would that do to S.L.R. sales?
Finally, there’s physics. You can’t illuminate the entire surface of a Wheat Thin-size sensor with a tiny lens that’s only half an inch away.
Anyway, you can probably guess what all of this is leading up to: somebody finally did it. Sigma, an admired lens company that only recently started making cameras, has introduced the DP1: the world’s first compact camera with an S.L.R.-sized sensor inside.
It’s what’s called an APS-C size sensor, the same size as what is in pro cameras like the Canon 40D and the Nikon D300. It measures about 1 inch diagonally. (Nobody ever expresses sensor sizes in this simple, logical way — S.L.R. makers do it in millimeters, compact-cam makers use bizarre ratios like 1/1.8 inches — but they should. People, rise up!)
You would expect the DP1, therefore, to take spectacular pictures — and it does. The solidly built, black metal camera fits in your coat pocket (not, alas, shirt or pants), and yet it takes pictures whose color fidelity, clarity, detail and freedom from “noise” rivals the output of entry-level digital S.L.R.’s. The DP1 also easily delivers that special pro effect where the subject is in sharp focus, but the background is softly blurred — something most pocket consumer cams can’t manage.
Sigma would probably cite its use of the famed Foveon sensor as a reason for its photographic success. Each three-layered pixel on this sensor absorbs all three colors — red, blue and green. (Regular digicams use individual red, blue and green sensors parked side-by-side on a single layer.)
Photo nuts argue endlessly about the virtues of this arrangement, but one thing’s for sure: it makes calculating the megapixels of this camera very murky indeed. Sigma, counting three for each pixel (red/green/blue), arrives at 14.1 megapixels; counting each layered pixel as one yields 4.6 megapixels.
Here again, though, who cares? The point is that these photos have plenty of resolution for huge, grain-free prints, or liberal cropping away of unwanted background.
In any case, you may want to pause here for a moment to relish the happiness of Sigma’s achievement, because what follows is one crushing disappointment after another.
More at:
The New York Times
Utah? 
