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Sigma SD10 - Is 3.4 Megapixels Really 10 Megapixels? 
by Jim McGee

The new Sigma SD10 is essentially an update to the SD9 that we reviewed in issue #25. That update appears to address the biggest concern we had with the SD9 - namely it's inability to function in low light conditions - an absolute must for a pro-level camera.

Sigma's SD10 is the first camera to employ Foveon's updated version of the X3 image sensor. This new sensor supports an ISO range from 100 to 800, plus an extended mode option to ISO 1600, and exposure durations of up to 30 seconds (in extended mode). Max exposure durations in other modes are 15 seconds at ISO 100 and 4 seconds at ISO 200-800.

These are dramatic improvements over the SD9 which had an ISO range of only 100 to 400 and a maximum exposure time of 15 seconds at ISO 100 and a mere 1 second at anything other than ISO 100.

Another significant improvement is in the batteries. The SD9 carried two sets of batteries, the SD10 uses only a bottom battery tray that can be loaded with four AA or two CR-V3 batteries.

Exposure compensation was at half stop intervals on the SD9 and is at one-third stop intervals on the SD10 and wireless TTL flash is now available on the SD10 when used with Sigma's new EF500 Super/ST DG SA-N flash. Sigma's raw file format, X3F, now supports embedded shooting data (exposure compensation, contrast, saturation etc.). The SD10 also adds mirror lock-up, a Firewire interface (IEEE 1394), and the ability to shoot up to 30 frames in continuous shooting mode.

There have also been improvements to Sigma's Photo Pro software. Version 2.0 adds improved batch processing and browser functions and adds a digital fill light function, which brings up detail in shadow areas while preserving detail in highlight areas. If this function works as well as the samples we've seen it will be a valuable tool for SD10 shooters.

Fill Light sample image

All of which correct complaints we had or heard concerning the SD9. Our hats off to Sigma; they've obviously been listening.

We felt that Sigma did a good job on ergonomics with the SD9; always a tough proposition for a first generation design, and the ergonomics on the SD10 are largely unchanged.

But the biggest change is the jump in resolution from 3.4 megapixels in the SD9 to 10.2 megapixels in the SD10 - even though the image file size is the same for both cameras. You can check out our thoughts on this little piece of marketing wisdom below.

We're really looking forward to the opportunity to shoot with the SD10 in real world conditions. We thought Sigma did an admirable job on the first generation SD9 and it looks like they're only getting better.

F7X3-C9110, The Next Generation 
X3 Chip from Foveon

The 10 megapixel F7X3-C9110 is an enhanced version of the Foveon X3 image sensor that appeared in the Sigma SD9. The newest X3 sensor doubles the sensitivity and maximum exposure times of the old design and increases the dynamic range. These are important improvements as we found the SD9 to be virtually unusable in low light conditions.

Sigma's SD10 is the first camera to employ this new sensor, supporting an ISO range from 100 to 800, plus an extended mode option to ISO 1600, and exposure durations of up to 30 seconds. These are dramatic improvements over the SD9 which had an ISO range of only 100 to 400 and a maximum exposure time of 15 seconds at ISO 100 and a mere 1 second at anything other than ISO 100.

Foveon also claims "The X3 Pro 10M delivers the highest effective resolution possible without color artifacts for the 25mm optical format." This is something we'll be looking closely at during testing as color artifacts were a problem we found in the previous generation.

The 10 megapixel rating is a bit confusing when you look at the 2268 x 1512 resolution output of the F7X3-C9110 (which is unchanged from the original X3). 

2268 x 1512 is a 3.4 megapixel image. Foveon claims that since the X3 is capturing full color at each pixel location, rather than the RGB value captured at each pixel by other processors, that the X3 produces the equivalent of a 10.2 megapixel image.

Umm, right. This sounds like marketing speak to us.

Regardless of how an individual pixel is captured - and frankly I don't care as long as it's rendered accurately - I end up with a 3.4 megapixel image. Period. End of discussion. A 3.4 megapixel file is a 3.4 megapixel file. You can claim that the quality of your 3.4 megapixel file is better than the other guys, but in no way is your file magically larger than the other guys file.

Any other techno-speak you want to add around that fact is best applied with a shovel and hip-waders.

Certain techies are in love with this concept, and to Foveon's credit it has the potential to improve the quality of digital imaging. But as a photographer I'm concerned with image quality not microchip design. And I've got to say that the quality of images I'm seeing from Canon, Nikon, Kodak, Fuji, Olympus, etc. are pretty damned amazing. Based on our tests the original X3 didn't live up to Foveon's claims. I'll reserve judgment on the new X3 Pro until I can shoot with it using production cameras, using the same lenses, of the same tripod, under controlled conditions in the real world. That friends, is the only way to tell if there is a real, worthwhile difference.

In a conventional CMOS or CCD sensor each pixel is captured as either a red, green, or blue pixel value (RGB). Those red green and blue pixels are then combined in a matrix for build the image (top).

In the Foveon chip each pixel captures a color value composed of red, green, and blue values. This means that theoretically the Foveon chip captures 3X as much image information - but the end result is still the same number of pixels. But according to Foveon/Sigma the color of any individual pixel is more accurate, rendering sharper images with more accurate colors and fewer digital artifacts. 

When we tested the Sigma SD9 with the X3 chip against the D100 last year we found the opposite to be true. While the SD9 had a very slight edge in sharpness, the D100 produced more accurate colors with no artifacts. There were noticeable color artifacts in the SD9's images at anything over ISO 100. Low light performance with the X3 chip was very poor.

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