The Sigma DP1s takes the company's previous DP1 fixed-lens compact camera from 2008, and updates it with some of the firmware features of the subsequent DP2 model. In terms of hardware spec, the Sigma DP1s is largely unchanged from the DP1. Images are still recorded with a 3:2 aspect ratio, 0.98-inch Foveon X3 image sensor which captures full information at every pixel location, and outputs images with 4.7 megapixel effective resolution. The Foveon chip sits behind a wide angle 28mm-equivalent (16.6mm actual) fixed focal length lens with six elements in five groups, and a maximum aperture of f/4.0. Date from the sensor is handled by a Sigma 'TRUE' (or 'Three layer Reponsive Ultimate Engine') image processor - the same generation used in the DP1, rather than the newer 'TRUE II' chip that featured in the DP2.
The Sigma DP1s offers Auto, Manual, Program, Shutter- and Aperture-priority shooting modes, and determines exposures images via evaluative, center-weighted average and spot metering. The DP1s uses nine-point contrast detection autofocusing based on data from the image sensor, and also offers manual focusing capability. There are eight white balance modes available, including auto, custom and six presets. Sensitivity ranges from a minimum of ISO 100 to a maximum of ISO 800 equivalents. Shutter speeds from 1/1,000 to 15 seconds are available at maximum aperture, and as the aperture is closed, the fastest speed gradually increases to 1/2,000 at F10. As with the DP1 before it, the Sigma DP1s can store data on Secure Digital or MultiMediaCard media, including the larger SDHC types. Images can be written in either Raw or JPEG formats, but unlike many cameras these days, cannot write both formats simultaneously. Power comes from a proprietary BP-31 lithium-ion rechargeable battery, and connectivity options include both USB 2.0 high-speed data as well as NTSC / PAL standard definition video.
The changes made between the DP1s and its predecessor are subtle. The digital zoom buttons can now be mapped to provide a Quick Set function, as seen on the newer Sigma DP2 and SD15 cameras. Performance of the camera when shooting backlit subjects is also said to have been improved. The Sigma DP1s is expected to be available by the end of October 2009, and pricing has not been disclosed at this time.