Contrast, edge to edge clarity, resolution, light transmission, smaller sweet spot – across the board, the C Series has a slight decrease in performance, though still exceptional. This will be most noticeable when spending longer time behind the glass. The internal optical system uses a mix of glass grades and coatings. While the B Series are produced and built individually, the C Series is produced in the hundreds, and are sample inspected, rather than individually inspected. The polymer frame makes the C Series lighter than the B Series.