All using Voigtlander 40mm Ultron II Nikon mount @ f/8, same physical exposure, tungsten lighting, shot raw and processed in LR5 with all defaults, downsampled to 8MP. For A7/A7r ISO 51,200 and 102,400, shot at max ISO of 25,600 and pushed 1EV and 2EV in LR. For Df ISO 409,600, shot at max ISO of 204,800 and pushed 1EV in LR. For A7/A7s, EFCS used for all images.The Df's output brightness in LR was a little below the A7 models and so was adjusted +.15EV in LR.
100% Crop Composite #1
100% Crop Composite #2