Sigma SD15 Overview
First announced in September 2008 at the Photokina tradeshow in Cologne, Germany, the Sigma SD15 is a direct successor to the now rather long-in-the-tooth SD14 model, which was announced in September 2006 and started shipping in March 2007. The Sigma SD15 retains the same near-APS-C sized (0.98 / 24.9mm diagonal) Foveon X3 image sensor from the SD14. This imager features 14.1 million 7.8µm photodiodes, and is capable of measuring full RGB color information at every pixel location. The Sigma SD15 hence outputs a 4.64 megapixel maximum image size (with the interpolated "Super High" 4,608 x 3,072 pixel mode having been dropped from the spec sheet). The reduced-resolution Raw modes are also no longer listed on the spec sheet and hence possibly removed from the camera, with the native 2,460 x 1,720 pixel resolution now the only listed Raw option.
The SD15 will mark the debut of Sigma's TRUE II ("Three-layer Responsive Ultimate Engine") image processor in an SD-series camera body, with the Sigma DP2 having been the only model to feature the TRUE II processor to date. (The original TRUE processor featured only in the DP1 and DP1s compact cameras. Previous SD-series DSLRs have featured an unbranded image processor.) The Sigma TRUE II processor is said to offer improvements in processing speed, operation, and performance.
Perhaps the most obvious change when looking at the SD15 compared to its predecessor is on the rear panel, where there's a new larger 3.0-inch LCD panel with a significantly higher resolution of 460,000 dots, versus the 150,000 dot 2.5" panel of the SD14. The rear-panel controls have also been restyled somewhat, and the functions of some of the individual buttons shifted around to fit in Sigma's Quick Set button as seen on the newer DP-series compacts. The only other obvious change externally is a flash card indicator lamp towards the bottom right corner of the camera's rear panel, although upon opening the flash card compartment a switch from CF / Microdrive to SD / SDHC / MMC media (but not the newer SDXC type) also becomes apparent. Overall body size is unchanged, but the SD15's weight has fallen by 20 grams or 0.7 ounces, impressive given the larger LCD display (and quite likely achieved thanks to the switch to an SD slot.)
Quite a few firmware changes have also been made since the SD14. The previous camera's ISO sensitivity range of ISO 100 to 800 equivalent plus an expanded ISO 1,600 position has been replaced by a new default range of ISO 100 to 1,600, with the ability to expand the outer limits to an ISO 50 - 3,200 range. There's also now an ISO Auto position which selects between ISO 100 or 200 ordinarily, and as high as ISO 400 when using flash. The SD14's evaluative, center, and center-weighted average metering modes have been replaced by a selection of evaluative, center-weighted average or spot metering. The SD15 also now offers a choice of seven different color modes - Standard, Vivid, Neutral, Portrait, Landscape, Black and White, and Sepia. The SD15 is now listed as DPOF compatible, allowing creation of print orders on the flash card which can then be understood by certain printers. Finally, the Russian language has been added to the list of available choices in the SD15's firmware..
The Sigma SD15 began shipping in late June 2010, with street pricing in the region of US$989.