Antonio F writes from Italy:
I am waiting for the Sigma sd Quattro H, of which I think you will do a test, because I love the Foveon sensor; I am very doubtful whether to buy this camera or Sony A7R II, considering the fact that the X3F files must be developed with their very slow software.
I photograph mostly nature and landscapes and I would like some advice from you, especially about the image quality; what would you do regardless of the price? Many thanks for your kind reply.
DIGLLOYD: this is a complicated issue that is not easily summarized (lens size, lens selection, dynamic range, battery life, raw file size, camera speed and operational characteristics, etc).
As for raw files, Sigma has stated that DNG support is in the works. Whether the DNG format is fully as good as X3F remains to be seen. There are also at least two programs that convert X3F into TIF: Iridient Developer and Graphic Converter.
To give a brief answer, one that that assumes image quality as good as the Sigma sd Quattro but with 25 megapixels captured: shooting the Sigma sd Quattro H over the Sony A7R II has a lot of merit, and is definitely one worth of consideration—the images I obtained with the Sigma dp Quattro cameras last fall were outstanding, and that was with the smaller APS-C sensor.
The main lens drawback: the large and heavy f/1.4 Sigma Art primes (and 12-24/4 and 24-35/2), which are huge compared to the Zeiss Loxia lineup. And there exist no other options (for high quality). I wish that Sigma offered an ultra high performance f/2.8 lineup because the f/1.4 Art lenses are just too large and heavy to carry more than two or three at most. Dynamic range was not an issue for me, but having the sun in the frame is one significant drawback (weird sensor flare).
Another option is fixed-lens cameras like the Sigma dp Quattro line. I hope that there will be a Sigma dp Quattro-H lineup with the larger APS-H sensor along with lenses optimized for that larger sensor—the lenses on the dp Quattro cameras are first class and not easily matched by interchangeable lenses in size/weight or performance.
The fairly exciting thought would be a full-frame Sigma sensor around 36 megapixels, which would surely blow away any DSLR on the market. But I don’t expect a full frame Sigma sensor any time soon, and the files would be around 300MB each!
Suggestions below are mostly missing due to data limitations from B&H. The keys lenses to consider for the Sigma sd Quattro H are the Sigma 12-24, Sigma 24-35 and the Sigma 50/1.4 and 85/1.4 primes (SA mount for Sigma sd). See reviews of those lenses in DAP.