Exploring the dynamic range of the Ricoh GR, I came across an ugly behavior (using the DNG raw format into 16-bit TIF).
My suspicions are detailed in my Ricoh GR Digital: Circular Ring Artifacts.
Ricoh GR is available at B&H Photo for about $800.
Bruce D writes:
Those rings look suspiciously like lens artifacts - perhaps caused by improperly cast aspheric elements (or perhaps by poor polishing of the spherical ones.)
DIGLLOYD: yes, they do look like polishing rings on aspheric lens elements, and the Ricoh GR lens has two aspheric elements, However, this theory leaves me puzzled as to why the interiors would alternate in density (brightness). Perhaps it is due to a slight angular difference, from the polishing. It is a plausible theory, though I am not fully persuaded as yet.
Update Feb 14, 2014
Ricoh has responded and there is a firmware update.