This lens is being strongly considered for purchase, and would like some feedback from those out there using this lens. Rodenstocks are known for a "sweet spot" at f8 - is this true for this lens? Also, as you go up to f16, does the image quality degrade significantly or is it a moderate decline? I know the latter question is rather open ended, but some feedback would be great. Are any of you using this lens at f16?
Thanks!