The GXR is a totally new style of camera in which the image sensor, lens, and image processing engine are part of the interchangeable units, so there is no image sensor in the body itself. According to Ricoh this brings several benefits over conventional SLR designs (and their newer 'mirrorless' equivalents): Portability, Image quality (optimum lens/sensor combinations) and Expandability (the possibility to add other units to the body, such as a compact projector or high capacity storage unit). Having a totally sealed unit also means that dust ingress simply cannot be a problem.
It's not a totally new idea - back in 1998 Minolta launched an interchangeable lens unit camera (the Dimage EX-1500), but it's certainly like nothing else on the market today. The key points are simple: the lens and sensor are bought together in a single, interchangeable sealed unit, with different units containing different sensors, up to a maximum APS-C (the same as most mid-range digital SLRs) - smaller sensors for zooms, larger sensors for primes. You're basically buying a new camera with every lens (tempting me to start referring to the GXR as an 'interchangeable camera' camera).
The diagram above should give you some idea of how the various processes and parts of a modern digital camera are split between the lens unit and body. In addition to the actual optics, the lens unit contains the CCD or CMOS sensor, focus and zoom motors, an image processing engine, buffer, gyro sensor (for image stabilization) and a fast, wide data path to the body. The raw data is then passed to the body (which contains all the other stuff you'd normally find in a camera), where it's processed (if you're shooting in JPEG mode) and saved to a file on the card.
The slide mount is simple and solid, but feels totally alien to anyone who has spent a lifetime with bayonet mount lenses.
The first lens units
The GXR body doesn't even qualify as a camera without the addition of a lens unit, and at launch Ricoh is offering two of them; one sporting a 50mm (equivalent) F2.5 macro prime and a 12MP CMOS APS-C sensor and the other a 24-70mm (equiv) F2.5-4.4mm with a small (1.175") 10MP CCD (at which point it's pretty close to being a bigger, more expensive version of Ricoh's own GX200 compact). It's also promising two more to be released during the course of 2010 - a 28-300 mm-equivalent F3.5-5.6 VC which uses a back-illuminated CMOS sensor, and a 28mm-equivalent F2.5 wideangle with a a 12Mp APS-C sensor.
Because the units contain both lens and sensor, they're designated in a fashion which describes both. The naming convention is fairly simple once you know how:
The sensor is described using a letter for its size (A for APS-C, S for 1/1.7", and P for 1/2.4", at least so far) plus a number for its megapixel count.
Next comes the lens's focal length, expressed as a 35mm-equivalent (which is sure to annoy the pedantic, but allows easy comparison between units), followed as usual by its aperture.
Hence the A12 50mm F2.5 Macro uses a 12Mp APS-C sensor and a 50mm-equivalent F2.5 lens (which actually has a real focal length of 33mm).
Below you'll find the specifications of the two initial lens units (note that these specifications are only applicable when the unit is actually attached to the camera, as some functions are controlled / defined by the body):
The size of the lens - and thus the camera - is down to the size of the sensor inside: on the left is the 24-70mm (small CCD) zoom (collapsed - it extends when in use) and on the right the 50mm (large sensor) prime. Both have a maximum F2.5 aperture. Size or quality: you decide.
50mm F2.5 GR
S10 24-72mm F2.5-4.4 VC
A12 50mm F2.5 MACRO
Focal length (35mm equiv.)
(ND filter used for apertures of f/22 in auto shooting mode)
11 elements in 7 groups (4 aspherical lens elements)
• 640 x 480
• 320 x 240
• 30 fps
• Motion JPEG AVI
• 1280 x 720
• 640 x 480
• 320 x 240
• 24 fps
• Motion JPEG AVI
Battery life (CIPA)
DB-90: approx. 410 shots
DB-90: approx 320 shots
68.7 mm × 57.9 mm × 38.6 mm (excluding projections)
68.7 mm × 57.9 mm × 71.3 mm (including the lens barrel; excluding the connector)
The S10 zoom lens accepts Ricoh's wide and tele converters. Other options include a clever lens cap (LC-2) that opens when the lens extends and a lens hood (HA-3). We didn't get to see either of these 'in the flesh'
The A12 50mm module has a neat built-in lens hood, and also accepts 40.5mm threaded screw-in filters.