Olympus E-1: Digital SLR with an edge

The E-1 uses a rechargeable lithium ion battery, but it only provides enough power for about 150 shots. For extended shooting, the optional BLL-1 battery pack ($399) holds two batteries and adds a vertical shutter release.

One plus one equals Four Thirds

For years, Olympus has been the leading voice of damnation against the failings of older lenses paired with digital SLRs, a problem that apparently stems from the distinct ways that film and digital sensors capture light. In film, silver-halide grains located in multiple emulsion layers are sensitive to light coming in at all angles. This gives film an increased sensitivity to light focused at different depths of the emulsion, a common occurrence with spherical lenses. However, light-sensitive CCD pixels sit along a perfectly flat plane, in the bottom of a well, and are most receptive to light focused on the micro lenses covering each pixel.

According to Olympus, light from the edges of a wide-angle spherical lens set to a bright-aperture setting (f/1.8-4.0) may not focus precisely on the perfectly flat CCD. This can lead to measurably lower resolution, contrast, and color accuracy around the edges and corners of an image.

How to overcome this problem? We've found that setting a lens to f/5.6 or higher can dramatically reduce the edge effects on a digital SLR by increasing depth of field at the sensor. But it's not always possible, or desirable, to set the aperture higher, which is why Olympus decided to design the new Four Thirds system with the help of its imaging-sensor partner, Kodak. The name Four Thirds is derived from the 4:3 aspect ratio of the image sensor in the camera. (By this method, 35mm film could be called the Two Thirds system because of its 2:3 aspect ratio.)

Kodak's advanced 5.5MP, Full Frame Transfer CCD (measuring 17.3x13mm) was chosen because of its 4:3 aspect ratio, its high resolution, color accuracy, and low noise. (Its narrower horizontal field of view, relative to the vertical axis also helps reduce edge effects.) Then Olympus optimized the design of their new Zuiko Digital lenses for this flat CCD using aspherical elements and high-quality ED glass. According to Olympus, true wide-angle lenses such as the Zuiko Digital 14-55mm f/2.8-3.5 (equivalent to a 28-108mm lens on a 35mm camera) have less distortion, reduced light falloff, and more accurate colors around the edges at wide apertures.