The Rodenstock APO-Sironar S 135mm f/5.6 is the premium version of the 135mm normal-to-wide lens, with a slightly larger 208mm image circle compared to the N version's 200mm. At 240g with a 49mm filter thread, the S designation indicates Rodenstock's top-tier APO-Sironar line with enhanced optical performance at wider apertures and across the full image circle. It delivers superior edge sharpness compared to the N variant.