Now in hand is the Sigma SD1 Merrill (about $2299) with its Sigma/Foveon true-color sensor, along with the new Sigma 18-35mm f/1.8 zoom (designed for APS-C), and the Sigma 35mm f/1.4 DG HSM. The 18-35mm has the same attractive fit and finish as the 35mm f/1.4 DG HSM.
The sensor in the SD1 Merrill is the same sensor as found in the Sigma DP Merrill compacts. See the recent blog piece: Pixel for Pixel, *Nothing* Beats a Sigma DP Merrill.
My intent in requesting this gear (thank you Sigma) was and is to test infrared shooting with the Sigma SD1 Merrill, because it is trivially converted to infrared by removing the internal filter inside the mirror box, and this is just as easily reversed. So it is the only stock camera on the market (excepting certain medium format cameras) which can be user-converted to and from visible light and infrared use. But with the 18-35mm zoom, I am now also planning to also shoot visible light with the 18-35mm and the 35/1.4 and to document their performance on the Sigma/Foveon APS-C sensor.
Removal of the blocking filter means that the camera might see in “full spectrum” also: visible light as well as infrared, and possibly ultraviolet as well when using the UV-transmitting Coastal Optics 60mm f/4 UV-VIS-IR APO Macro (modern lens coatings strongly block UV with most lenses). This means that the lens requires a filter to achieve the desired spectral transmission (e.g., infrared pass or infrared block or UV pass). But the Sigma mount cannot take my Coastal 60/4, so performance in true UV cannot be tested.
Considering that a DSLR infrared conversion costs $350 to $500 to do right and is not easily reversible, the ability to convert and deconvert the SD1 Merrill has appeal, as does the unusual sensor. Whether the sensor performs well in infrared remains to be seen, but I expect exceptional results with proper filtration, possibly in false color, but certainly in monochrome.
Shown below, the Sigma 18-35mm f/1.8 DC HSM (about $799 for Nikon, Canon, Sony Alpha, Sigma, Pentax). Lens designed for APS-C sensors.