Horizontal cuts through the umbrae at y = 203.6′′ north of apparent solar disk center for BIMA image at 3.5 mm a), for BBSO Ca ii K image at the original resolution b) and at 12′′ resolution of the mm image c). Thick solid lines mark the location and size of the two umbrae. Thick dashed lines correspond to the potential reduction of the mm umbral brightness when going to 4′′ resolution. The QS level is indicated by the thin dotted lines.