Nikon has launched the D3S, a digital SLR for professional photographers that's extends the capabilities of the popular D3 model by offering improved low-light performance and adds HD video capture.

The D3S features a completely re-designed 12.1 effective megapixel image sensor. The large pixel pitch, with a completely modified inner structure, means that the D3S can capture images under light conditions which were previously believed to be impossible, according to Nikon. The seven-stop ISO range of 200–12800 enables image and movie capture in extremely low ambient light conditions.

There are also three additional ISO boost levels, up to Hi-3 with an ISO equivalent 102,400.

The D3S's FX-format sensor and wide-aperture Nikkor lenses make it a very capable video camcorder, says Nikon. Movies are captured at 720p/24fps using motion-JPEG compression with stereo sound using the input jack. Files are captured in AVI format, which enables a unique ‘Save Selected’ frame option that save a still from the video alongside the clip.

At an event to launch the camera, a Nikon spokesperson blamed the 2GB size limitation of the AVI format for not including 1080p capture, as recording in 1080p would have severely reduced the maximum video capture time of five minutes.