Fujifilm X Lens XF18mm F2 R
Compact and lightweight "Pancake" type.
Using glass-mold aspheric lenses at the 5th and 7th elements,
is effective to in increasing the maximum aperture (5th element)
and reducing the overall thickness of the lens (7th element).
The final element, positioned as closely to the sensor as possible, makes the incidence angle of light reaching the sensor smaller, and reduces vignetting and color shading, while helping to keep the lens's overall size small.