Most of these issues are relatively minor problems. The actual challenge for photographers new to Sigma cameras is that some of the operational controls of its models are unique to Sigma.
The most evident is that the SD1 includes twin screens to change the main settings, while other DSLRs have only one or the other. Both the Function button and Quick Set (QS) button provide access to an interactive settings display. Navigation of the screen generated by the Function button requires multiple-button pushing, but all the shooting settings are seen. In addition, a diagram appears with the selected auto-focus (AF) point and the relationship of it to the light-metering pattern. A push of the alternative Quick Set button transforms the buttons of the four-way controller into shortcuts for specific operations. Press the QS button again and a second set of options appear.
The direct-access buttons also have some challenging quirks. Those buttons provide access to ISO, metering, AF point, exposure compensation and flash-exposure compensation by holding down and spinning the appropriate control dial. For whatever unknown reason, all the dials are easy to use, except for the ISO button. All the buttons can be operated while looking through the viewfinder, since a menu option on the back of the camera reveals the change of settings, which can also be seen in the viewfinder. The quirk here is that the settings seen with the Function button are visible, but the four-way controller no longer manipulates them; the dials suddenly take command.
Quirk #2 of the direct-access buttons is that when the camera is in either Shutter-Speed or Aperture Priority mode, both control dials are specified for the selected parameter. The exposure compensation button must be pushed to shift from the metered exposure value. A better solution might have been to designate one dial for exposure compensation or make it possible to configure as an option. Again, this is not a major hurdle, just a Sigma “thing,” with which one must become familiar.
Quirk #3 is simply puzzling: Why is there a button for metering mode when White Balance would have been more useful?
Another issue that potential buyers of the SD1 must weigh carefully is that the camera has a Sigma SA lens mount. Although the company offers many lenses that accept this mount, the question is: Do the Sigma lenses have specifications for sharpness, etc. that match a $9,700 camera?
Because the SD1 is designed solely for still photography, it includes basic connectors: DC power input, remote control socket, USB/AV connector and a flash-sync port.
There is no denying that the Sigma SD1 is a camera for a niche market, first because of its conventional functionality and second because of its price. Some photographers that may have been in that niche will be disappointed that the SD1 is not comparable in price to a Nikon DX300, for example. For serious photographers looking for a medium-format alternative, however, the Sigma SD1 deserves investigation and consideration.