Epson R-D1

The original R-D1, announced by Epson in March 2004 and discontinued in 2007, was the first digital rangefinder camera. Subsequently, three modifications of the original "R-D1" were produced - "R-D1s", "R-D1x", and "R-D1xG".
R-D1.
"R-D1" was jointly developed by Seiko Epson and Cosina and manufactured by the latter, which also builds the current Voigtländer cameras. It uses Leica M-mount lenses or earlier Leica screw mount lenses with an adapter.
An unusual feature to note on the "R-D1" is that it is a digital camera that has a manually wound shutter with a rapid wind lever. The controls operate in the same way as film-based rangefinder cameras.
Data such as white balance, shutter speed, picture quality, and shots remaining are all displayed with servo driven indicators on a dial like a watch face (made by Epson's parent company Seiko). With the rear screen folded away, it is not obviously a digital camera.
"R-D1" and all of the subsequent modifications of the camera have been using the same 1.5x crop factor sensor, interline-transfer CCD (Sony ICX413AQ). The same sensor as used in Pentax *ist D, Nikon D100. Sensor originally dates to 2002.
R-D1s.
The successor of "R-D1", the "R-D1s" was released in March 2006. The "Epson R-D1s" is mechanically identical to the "R-D1", but with a firmware upgrade. It adds:
Users of "R-D1" could upgrade their camera to have the same functions.
R-D1x.
The successors of the "R-D1s", the "R-D1x" and "R-D1xG" were made available from 9 April 2009 in Japan only. They feature very similar feature set except for few modifications:
On 17 March 2014, Epson announced that the "R-D1x" is discontinued.