The review was of the Sigma DP3 Merrill, written from the perspective of a monochrome specialist. I learned a few things about the Merrill's colour response, and the benefits of using Sigma Photo Pro[cessor] to convert images to monochrome instead of moving a colour tiff to Lightroom. The Foveon sensor is unusual by having vastly different amounts of noise in different colour channels, so doing the conversion in SPP can make a very big difference to the noise levels.
The photo on the left is the out-of-camera jpeg that has had its tones adjusted to match the converted-from-X3F tiff on the right. The raw image was significantly improved by selecting the blue channel, making the otherwise unusable iso800 remarkably clean even though I'm using the minimal noise reduction setting.
Usually the Merrill gives me a high-iso quality level about four or five stops below my D800, but this may give me another stop or two of usable range for photos that I know will be in monochrome.
Just for fun, here's the camera jpeg. It doesn't look vastly different at this size, except for some rougher tonalities, but at larger sizes the change is more dramatic. I'm not afraid of grain, but this is starting to show banding. Yes, at iso800.
I learned shoot raw+jpeg with the Merrill fairly early on. I load the jpegs into Lightroom so that I can use them as a preview, and switch back and forth to SPP to process the raw images. The only catch is that the image size settings – where I would normally choose a small jpeg – affect the raw image, as well. On the other hand, it's nice to have a full-sized jpeg, and it's not as if reducing the jpeg size really makes a difference to the Merrill's file size or writing times.
The Merrill isn't like other cameras, but it's worth it.