Ricoh GXR A12 50mm f/2.5 macro review

It's not often that something completely new comes along in the digital camera market, but Ricoh's GXR unit camera system certainly fits into that category. Traditionally, cameras have either had fixed or interchangeable lenses but Ricoh has opted for a quirky new slide-in mounting mechanism that allows you to change both the lens and sensor.

The growingly popular micro four thirds system cuts out the bulk by removing the mirror box in a traditional SLR, but Ricoh's GXR uses a completely different take. Each GXR lens unit is completely sealed and includes not only a lens, but also houses the sensor, shutter, aperture blades, the auto-focus motors and an image processor. There's another image processor in the GXR body as well, which appears to handle the bulk of the in-camera processing, but this will ultimately depend on what unit is attached to it.

So far, Ricoh has released two lens units and has announced that another two are in development. We've got both of the released lenses here and since changing the lens effectively turns the GXR into a new camera, we're going to look at them separately.

The first of the two is the A12 50mm F/2.5 macro, which uses a 12.3 megapixel APS-C CMOS sensor (the same size as a DSLR's sensor) and costs around £600 if you buy it separately from the GXR body. The second is the S10 24-72mm F/2.5-4.4 VC, a 10 megapixel 1/1.7in CCD sensor with sensor-based image stabilisation, which costs £325 - we'll be looking at this in due course.

The result of this is a camera, or series of cameras, that can cater for specific needs because each lens can be precisely tuned for the sensor it's attached to. This should mean better colour reproduction and less noise, and there's also the fact that you will never have to worry about dust getting on the sensor while changing lenses.

There are downsides to the system as well, as all of the lenses use contrast detect auto-focus, which is painfully slow on the A12 50mm unit and it's also not as accurate as we would have hoped. Quite often, the auto-focus system hunts around for the best subject, but this isn't completely accurate either. There were times where the camera focused on completely random objects despite pointing the camera at a person in the centre of the frame in reasonably good lighting conditions. The only time we didn't encounter problems such as this was in almost perfect light.

The solution was to set the GXR to continual focus, but that reduced the its already mediocre battery life significantly because the AF motors were running all of the time. We also found that selecting a specific focal point helped, but again didn't completely solve the problems inherent to this type of AF system.