Digital image sensors work best when the angle of incidence of the light falling on them is very high, preferably nearly perpendicular to the plane of the sensor. All of the digital SLR manufacturers now make lenses specifically designed to compensate for this by moving the rear element of the lens further away from the sensor. The R-D1 is designed to use Leica M-bayonet lenses, which as I mentioned earlier protrude well back into the camera body, which means the rear element is quite close to the sensor and the angle of incidence of the light striking the sensor near the edges is very low.
This sounds complicated, but what it means is that the images produced by the R-D1 with a wide angle lens are noticeably darker towards the edges of the frame, and I mean noticeably. It is possible that the vignetting might be less apparent with longer lenses, but as it stands the R-D1 will have major problems with at least half the lenses it is designed to use, making it almost useless for serious photography. Since it is specifically targeted at the professional and enthusiast amateur market, this has got to be something of a handicap.
There are other problems, including the camera occasionally freezing for no reason, inconsistent exposure metering and the lack of any cleaning mode for the dust-prone CCD. Ironically noise control at high ISO is very good, and the overall sharpness of the Voigtlander lens is simply fantastic, but sadly these cannot compensate for the vignetting issue.
As I said, I really don’t get the point of this camera. The kind of person who loves their Voigtlander Bessa is unlikely to ever commit the blasphemy of going digital, and anyone used to a modern digital camera will find it awkward, clumsy and unpleasant to use. Both will be massively disappointed by the poor image quality. My apologies to Epson, but the R-D1 is an expensive, badly conceived white elephant that should never have made it off the drawing board in its present form.
The Epson R-D1 is an exercise in nostalgia for people with more money than sense. Brick-like handling, poor results and a major inherent design flaw make it an expensive and pointless novelty item. The only analogy I can think of would be stuffing a turbocharger into a wood-framed Morris Traveller and then asking the same price for it as a brand new Mercedes. Who’s going to buy it?