This had +2/3 exp. comp and still needed half-a-stop more. I always get suckered into underexposing by the histogram, which is based on the camera-processed jpeg.
Next time...!
(hmm - I hear the LCD display on the 5DMkII is much much better ;-))

And I'd forgotten just how much the 24-105 vignettes at the wide end. Another reason to buy something shiny and new, for Christmas, perhaps...