Sigma DP2Image sensor size isn't the only thing that matters.
Aug 2, 2009
By Dan Havlik
As with the DP1, there's a 3 frames per second "continuous" shooting mode—which is about average for this class of camera—though the DP2 will lock up for about five seconds when shooting JPEGs as the images are transferred from the camera's internal buffer to the card, and for about 10 seconds when shooting in RAW. This is slightly better than the DP1 owing, perhaps, to the camera's new True II image processor.
Other stumbling blocks include the DP2's antiquated menu system which put all the camera's functions on one massive menu page which you need to scroll down through to find the appropriate setting.
The 2.5-inch LCD (230,000 pixels) seemed ok last year but in the 2009-era of 3-inch touchscreen LCDs with razor-sharp image playback, it now seems woefully outdated on the DP2.
What seemed a revelation about the DP1 just a year ago—its top-notch image quality—failed to impress me as much this time around on the DP2. The sensor is identical in both cameras—a Foveon X3 CMOS image sensor which Sigma rates at 14 megapixels.
In case you haven't followed the intricacies of Foveon X3 sensor technology vs. typical image sensors in the last five or six years, an X3 sensor is designed to mimic the look of film by directly capturing three layers of red, green and blue light at each point in an image during exposure. A "Bayer-pattern" sensor such as a typical CMOS or a CCD captures red, green and blue separately at different photo sites which are then reconstructed through interpolation to create color.
While Foveon X3 sensors and the Sigma cameras that use them have a small but devoted following, they're not without their controversies. In particular, there hasn't been much agreement on how to rate resolution on these unique sensor sandwiches. Foveon and Sigma triple the amount of pixels on their chips—because of the three layers—making a camera such as the DP1 and the DP2, which technically have a resolution of 4.6 megapixels, into approximately 14-megapixel cameras.
While there are some out there who insist on describing these Sigmas as 4.6-megapixel cameras, they are in the minority. Most of the conventional wisdom is that the sensor in the DP1 and DP2 can capture about as much resolution as a comparable 8- or 10-megapixel camera and I'm with them on that.
As with the DP1, I found that to get the best image quality out of the DP2 you really have to shoot in the camera's 12-bit RAW X3F format. JPEG images I captured with the DP2 looked overly processed and dull. RAW images, however, had fantastic depth and sharpness. (There's still no RAW+JPEG shooting mode on the DP2, by the way.)
Foveon devotees often speak of the "3D Effect" in their images and this is honestly something I've noticed in photos I've captured with Foveon-based cameras. The level of sharpness when shooting with a very broad depth of field—at f/14, for example—and the subtlety of shadows around the subject created a three-dimensional quality in some images I shot with the DP2, a look which I found quite pleasing.
I first noticed this effect years ago while photographing protests at the 2004 Republican Convention in New York City with the Sigma SD-9 DSLR. In a sea of thousands of faces, I was able to see clearly each individual expression and how deep the crowd extended down Seventh Avenue in my images. I noticed a similar look in photos I captured with the DP2 of the jam-packed Mercat de Sant Josep de la Boqueria market in Barcelona, Spain, and in the hordes of sunbathers on the Great Lawn in New York's Central Park.
Strangely, color has never struck me as a particular strong suit of these layered Foveon chips. Prior to processing, many of my images captured with the DP2 had a yellowy tint to them and colors looked flat.
After working on the RAW images in Sigma Photo Pro 3.3—the company's painfully slow RAW conversion software—I was able to get the color I wanted but it took a while. (Yes, patience is the name of the game when dealing with these cameras.)
I was also disappointed that while the maximum ISO had increased to 3200 on the DP2, images shot at 800 and above were riddled with ugly specks of noise.
This noise problem is similar to what I experienced with the DP1 which is odd considering the large X3 sensor with individual pixels at an impressive 7.8 microns in size. My guess is that because Foveon X3 sensors do not use anti-aliasing (aka "blur") filters since their three-layer design is less likely to produce color artifacts in images, they could be more prone to luminance or "light" noise.
Whatever the case might be, the distracting luminance noise I saw in even my ISO 800 images was disappointing. At ISO 400 and below in good lighting, this wasn't a problem but that's not saying much. Most compact cameras with much smaller conventional sensors can take a pretty clean photo in good light.
THE BOTTOM LINE
So here we are again with yet another intriguing but flawed camera from Sigma that uses the still intriguing but flawed X3 sensor from Foveon. Years ago when these layered Foveon sensors first appeared on the scene, they were hailed as the next big thing in digital imaging, something that would finally be able to capture the color and dynamic range to rival film. Nowadays with full-frame cameras such as the Nikon D3X and Canon 5D Mark II capable of producing images of such stunning clarity and color, that old argument about trying to "mimic" the look of film with digital sounds specious. While I continue to admire Sigma's devotion to putting a larger imaging sensor in a smaller camera—something their well-funded rivals are still, apparently, incapable of doing—I'm afraid the DP2 has too many liabilities for me to recommend it. If you're still interested in finding out what all the fuss is about with this technology, seek out the lower-priced, wider-angled Sigma DP1 instead.
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