See yesterday’s post Ricoh GR Digital: Circular Ring Artifacts.
I’ve published a second example of the Ricoh GR concentric ring artifacts, this time with RawDigger histograms for RGB/red/green/blue as well as the raw histogram. This approach eliminates Adobe Camera Raw as a factor, and proves that the artifacts are present in the DNG raw file to begin with.
Working theory: polishing rings from aspheric lens elements.
Ricoh GR is available at B&H Photo for about $800.
Update Feb 14, 2014
Ricoh has responded and there is a firmware update.