Ongoing debate on DPREVIEW after a "Photo comparison between DP2M and new SDQ H with 35mm Art"

Big discussion on dpreview...
https://www.dpreview.com/forums/post/59286776
...about the "shadow quality" and colors based on a DP2m photo that is underexposed by 2 stops.

Exposure: Manual - 1/1000 - F6.3 - ISO: 200
...doesn't make any sense.

Sigma sd Quattro H vs. Sigma sd1 Merrill image comparison

Maro provided an image comparison between the sdQH and the SD1 with the 85mm 1.4 Art lens:

http://maros-notebook.txt-nifty.com/notebook/2017/01/sd1-vs-sd-qua-2.html

At first, the images look quiet similar. But the statements in the dpreview forum are pretty harsh:

• "SD1 looks sharper!"
• "Not only sharper. In Quatro I see a lot of color artefacts."
• "If the SD1 had live view and an EVF, it would be the better camera.  Certainly it produces a better image."
• "Merrill was/is clearly outstanding!"
• "This just makes me think what sort of fabulous camera a mirrorless SD Merrill H would have been."
• "Once again the comparison show that 1:1:1 layers structure of the Foveon Merrill of the SD1 wins over the poor and rubbish 1:0.25:0.25 structure of the Quattro"
• "The SD1M will be my last Foveon camera unless Sigma resurrects the Merrill chip in an improved body."

While the Quattro in general seems to have an edge regarding luminance resolution, many people

seem to prefer the look of the Merrill generation.

So what is it?

Maybe these 200% crops help to understand:

(click images for full resolution)

Clearly visible how destructive the default luma-noise reduction setting works with Quattro files,

but then luma-NR off shows how noisy the Quattro is on pixel level. 

So, finding the balance between noise reduction and adding/lowering sharpness is the tricky part with Quattro, while the Merrill sensor seems to be more forgiving and stable.  

Image quality: SD Quattro low-res vs. DP2 vs. Fuji X-E1 (downsampled)

Tom Schum from the dpreview forum made a comparison between these cameras:
SD Quattro (low resolution 1:1:1 Foveon structure) vs. the original DP2 and the Fuji X-E1 (downsampled)

https://www.dpreview.com/forums/post/58888373

Some people claim, if you want true 1:1:1 Foveon quality with the sd/dp Quattros, you should use the low resolution mode. 

Lets have a closer look at 200%: (ignoring the Fuji)

    click image for full resolution:

The sd Quattro sample looks sharper. (probably different sharpening amount) 
But have a look at the red and yellow surfaces of the boats.
The dp2 looks natural, smooth and realistic while the sdQ is noisy and shows posterization.

Quattros shortcomings are evident even in low res (aka true 1:1:1 Foveon structure) which leads to the conclusion that the sensor itself is flawed. 

Additional information:

A new conversion from the sd Quattro image with luminance noise reduction set to minimum:

Posterization effect is reduced, noise/grid becomes more visible.

SPP 6.5.0 vs. SPP 6.4.1, noise reduction comparison

(....and why the sd1 Merrill is the better performer)

With the release of the new Sigma Photo Pro 6.5.0 Sigma made some changes in the noise reduction processing for Quattro cameras.

Sigma:
"It has an improved algorithm in noise reduction when developing RAW data for the sd Quattro series and dp Quattro series."

Let's see what has been changed:

click the image for full resolution

Conclusion:
-No changes when NR is turned off. (first row)
-Middle position: SPP 6.5.0 adds a slightly higher amount of NR. (but no improvement in the NR quality)
-Bottom: Again very slightly more NR applied.

And now the SD1:
To keep it simple, i only show the best two versions.
Top: best default setting for this image
Bottom: overlay of a monochrome (blue channel) image over the color image.

click the image for full resolution

Conclusion: 
-clearly better and cleaner rendering with less luminance noise on both SD1 samples.
(sharpness suffering a bit because of the mediocre edge performance of the 8-16mm lens)

Better ISO performance of the Quattro? Still a myth..

DNG Unterstützung für die Sigma sd Quattro

Nun ist es endlich soweit und Sigma öffnet sich (wieder) für Dritthersteller wenn es um das Bearbeiten/Entwickeln Ihrer RAW Daten geht:

https://www.sigma-photo.co.jp/english/new/new_topic.php?id=624

Als witzige Anekdote hier noch die Antworten einiger alter dpreview-Hasen, welche sich so gerne mit ihren persönlichen Kontakten zu Foveon/Sigma brüsten und gerne mal mit ihrem Hintergrundwissen prahlen, auf eben jene Frage nach einer möglichen DNG Untersützung: