The dual challenge of achieving high performance within a compact body. The solution: Fixed-type lens.
The X100 was originally conceived as a slim and compact camera for users to take with them wherever they go. When we first began considering the lens design, we examined the many possibilities from a variety of perspectives, for example, the aperture value and lens size in the case of a zoom lens and lens-body combinations in the case of an interchangeable lens system. As a result, we determined that a non-collapsible, single focal length lens was the ideal choice to meet our two goals of achieving the product concept and delivering the high level of quality demanded by professional users.
Regarding the focal length, we considered the 135 equivalent of 24mm, 28mm, 35mm and 50mm. For each length, we evaluated the relationship between the F value and lens size, capability to satisfy user expectations, and the breadth of their application. We selected the 35mm lens as the best match for the camera concept.
Road to the F2 aperture value.
Designing an F1.6 or F1.8 lens is not so difficult; however, in the case of a digital camera, even if an aperture larger than F2 is used, the light receiving elements on the sensor cannot effectively use the brighter portion of the incoming light because of low incident light gathering efficiency.
Also by choosing an aperture of F2, it is possible to achieve a higher MTF* level when the aperture is closed to F4, F5.6, F8, etc. In most photographic situations, we envisage that users will often use an aperture that is 1 to 2 stops higher than F2. Therefore, in designing the lens, we put a priority on capturing superior quality photos with exceptional expression of detail in the aperture range of F4 to F5.6.
*MTF: Modulation Transfer Function is an index of the image formation performance of the lens. The value indicates the ability to reproduce contrast over a range of spatial frequencies.
