I've heard again and again that Mamiya has made its sharpest, one could argue best, lenses for ther 6 and 7 series cameras. I want to ask, why? To me, it appears as if the only market for these cameras lies with amatuers, and yet Mamiya makes so much for the working pro. Why wouldn't they deliver the best that they can to the pros still using the RZ67 or 645? I would think there would be more money in that market, and that the pros would want the best tools for the job. I'm just confused. Enlighten me. Is there some inherent problem in the SLR design?