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.
What I do, with every camera, is test the metering calibration.
- set up a tri-tone chart and the camera such that the chart fills the frame and divides it roughly into thirds
- set the camera to manual exposure
- use a hand-held incident meter to read the light falling on the chart and compare that to the camera's internal meter
(In the case of my camera, the readings match to within less than .3EV.)
- make an exposure at that setting, then look at the capture with the intensity histogram displayed.
The peaks of the histogram should divide the scale into thirds. If they're shifted left or right, adjust shutter time to compensate in .3EV steps until you get a perfect, evenly distributed histogram.
- move the image files into your image processing tool of choice (Phocus, Lightroom, whatever)
- check them with the tool's histogram
Use the EV offset from the image that the histogram fit best to adjust your settings when you're shooting. It will always be the same offset. It's simply how the meter is calibrated relative to the ISO and the engineer's expectation of proper exposure.
G