Tuesday, March 11, 2014

Thoughts: Sigma DP Quattro

I've been thinking more and more about Sigma's up-coming DP Quattro camera series. This series replaces the DP Merrill cameras. As you may know, I own a Sigma DP2 Merrill.

There's been a lot of talk about the design differences. The Quattro series looks a lot different than the Merrill series. The Merrill cameras are basically rectangular bricks, while the Quattro cameras look more like a mid-1990's cell phone. I'm not sure which design is less-worse.
On A Brighter Day - Tehachapi, California
Captured using a Sigma DP2 Merrill.
There has also been some talk on speed, high-ISO and noise improvements. Merrill cameras are slow (especially at saving files to the memory card), and the Quattro is supposed to be faster. I've also heard that the Quattro is one stop improved at high ISO. Merrill cameras aren't very good above ISO 400, while the Quattro camera is supposed to be good up to ISO 800. In color images, there have been some strange noise issues on Merrill cameras above ISO 200, and those are supposed to be fixed on the Quattro cameras.

But none of that is what I'm thinking about. Specifically, I have been wondering about the redesigned Foveon sensor on the Quattro cameras.
Big Bear Sunset - Big Bear Lake, California
Captured using a Sigma DP2 Merrill.
The Merrill Foveon sensor is an APS-C sized sensor with three 15-megapixel layers, each sensitive to red, green or blue. The problem is that less light reaches the second and (especially) the third layer. The camera has to push the data from the bottom two layers (the green and red layers) in order to get a good image. At low ISO, this is not a problem or even noticeable. But it quickly degrades the image as one increases the ISO.

The Quattro Foveon sensor is also an APS-C sized sensor with three layers, but with 20-megapixels on the top layer (the blue layer) and five megapixels on the bottom two. The pixels are much larger (and more sensitive to dim light) on the bottom two layers, allowing for better noise control. In theory, because there is less degradation in the bottom two layers, you get better high-ISO performance and less noise problems.
Boulder Bay - Big Bear Lake, California
Captured using a Sigma DP2 Merrill.
But this is where I see a problem: I like that the Merrill Foveon sensor captures a full resolution image in each color layer. This is important for when I make black-and-white images. I can use the color channel(s) that I want to give the effect that I want to achieve. It is very similar to using color filters with black-and-white film. In fact, you can use those filters on Merrill cameras.

The Quattro Foveon won't be capable of this, at least not to the same degree as the Merrill cameras are capable. While I have little doubt that the Quattro camera will be better for color photography above ISO 200, I'm not convinced that it will be better for much else. Most likely it will be better in some respects and worse in others.
Three Green Leaves - Tehachapi, California
Captured with a Sigma DP2 Merrill.
Until the Quattro is released and people have a chance to use it, no one knows for sure what the image quality will be. People (myself included) are guessing what it will be, but no one knows. I'm very curious, but I also have my doubts.

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