Fuji continues to release pieces of information on the X100 camera:
"For the X100, spherical lens elements are used as much as possible, and one double-sided aspheric lens made by a glass moulding process has been adopted as the most effective element for delivering maximum performance.
The sensor has been specially customised just for this lens. Unlike film, the sensors of most digital cameras require incoming light to strike the sensor surface at an angle that is as perpendicular to the sensor surface as possible. Because this is difficult to achieve with a slim lens, the positioning of the microlens on the sensor of the X100 has been customised to allow the capture of light rays with up to a 20° angle of incidence.
In order to capture images with a beautiful "bokeh" effect with the background softly out of focus, a 9-blade aperture diaphragm has been adopted for the X100. The 4-blade shutter achieves a maximum shutter speed of 1/4000s. Because the X100 uses a lens shutter system, the camera is capable of high-speed flash synchronisation.
A sheet-type ND filter which can be switched on/off is built into the lens system. When switched off, the filter is retracted. The ND filter is the equivalent of an f-stop reduction of 3 stops or a reduction of light volume to about 1/8.
However, when shooting macro shots with an open aperture in the neighborhood of F2, spherical aberration tends to occur. It is therefore recommended that an aperture value of F4 is selected for macro applications."