After several forum entries regarding the narrow dynamic range of the Quattro, especially the small reserves in the highlights, I started my own comparison with the DP2 Merrill to literally see for myself. The whole venture turned out more difficult than I initially thought. At the first try (aperture priority), exposure times didn’t match. At the second try, I took pictures with both cameras in M-mode, adjusted equal aperture setting, ISOs and exposure times, but the pictures had different levels of brightness. Since I worked with natural light at the first and second try, I had to exclude this potential error source at the next attempt. I didn’t take any chance at the third try: M-mode and artificial light. The result: the Quattro is less sensitive at equal ISO level than the Merrill. Only if exposure for the Quattro pictures is set to +0,67 in SPP or Lightroom, the shots of both cameras look similarly bright.
I took 5 pictures with both cameras respectively: one with correct exposure according to DP2Q’s histogram, and four that were overexposed by 1, 1.33, 1.67 and 2 stops respectively. All photos were taken at ISO200, the native sensitivity of both cameras, where the dynamic range is highest. Subsequently, I tried to restore details in the highlights with negative exposure in SPP 6.0.6. For every overexposed picture, I adjusted negative exposure exactly with the value that the photo was overexposed with. Specifically, this means that for a photo overexposed by 1 stop, negative exposure of -1 was dialed in.
Let’s now turn to my interpretation of the results: the DP2Q picture overexposed by 1 stop could be effortlessly restored. With the „overexposure correction“ feature* enabled in SPP 6.0.6 (only available for editing Quattro X3Fs) you get satisfying results even for restoring pictures overexposed by 1,33 to 1,66 stops. Photos that are overexposed by 2 or more stops are beyond remedy even with „overexposure correction“. The DP2M seems to have 1/3 to 2/3 of a stop greater reserves in the highlights. Considering the fact that all DP2M shots are more exposed by 2/3 of a stop due to higher sensitivity, the DP2 Merrill’s or rather the Merrill sensor’s highlight headroom is greater by 1 stop.
* this feature was disabled in this comparison