Following on...Thanks for the lesson. I've got a rough idea how this stuff works. The difference in clipping indication between the camera and Phocus is huge (at least 0.5EV). So to take full advantage of the range I try to ETTR, but with the X1D this is involves far more guesswork and crossed fingers than with far more modest cameras. So I end up constantly underexposing.
At least that's my experience.
Do be aware that "ETTR" is a rather simplistic rule-of-thumb that was important at the beginning of the digital capture era in photography, when pixel counts were low and sensor dynamic range was more limited than now. The idea is that a digital capture sensor is a linear device and the eye's perception of light and shadow is not linear, it more naturally follows a logarithmic scale, such that when you take the linear input from a digital capture sensor and apply a gamma curve to render perceived differences in light and shadow as the eye needs to see them, if you capture evenly across the sensor's dynamic range, the gamma correction throws away a good bit of the data in the curve, more of it in the upper half of the range than the lower half, so it's better to bias the exposure to give more data in the upper part of the range in order to lose less upon correction. You should try to never hit saturation because all tonal distinction is lost there.
With today's much higher resolution, much greater dynamic range (14-15bit depth!) sensors, you have far more choice as to what "best exposure" for a given scene is, with tons of overhead at both ends of the dynamic range to work with. Correct exposure is not just exposing as much as possible without going to saturation ... you have choice in the matter, and there are subtleties in the relationships of tonal values that you can choose beyond the simple mantra of "ETTR".
In the little test example I did this morning to write up my calibration test clearly, the best match in the histogram of a tri-tone target came at .6EV more exposure than the hand-held and internal meter indicated. Checking the raw file in Lightroom, that's still FAR from being near the saturation limits that ETTR implies ... I could take the +0.6EV or even a +1.2EV exposure into the Develop module and add 2.5EV MORE exposure before seeing a saturation flag pop up, due to the raw data being nicely synthesized to 14bits per component.