ND in photography

Here in 2010, the still photography and motion pictures haave moved into digital age in a big way, but the basic of getting an image is still not much change from the past.
My proimarty working tool in the studio is still larger cameras, probably the Canon 1Ds III/Nikon D3X is the smallest. Of course the size of camera is not necessary related to what we do in studio, but it was a workflow developed over the years, medium format digital capture is still more efficient for us considering many factors.  So having to work with either a medium format digital camera and a heavy weight Canon or Nikon in fact give us familiar size and weight in actual work, yes, it is heavy, but it is friendly.
I am also constantly looking for a compact camera for snapshots in studio, and it has been a long serach and try, until recently the SONY NEX-5, which is used for this portrait.  The obvious missing element for the SONY is the lack of a hotshoe for radio triggering the studio flash, as well as the ISO setting started at 200, which will push us to use very small apature to get the same exposure as our main cameras - but at the loss of quality.
The radio slave on a hot/cold shoe is a problem easily solvable, although not ideal. We can put a red filter to the flash so it does not register much in final picture, or simply use a foil to deflect the flash light, then most of the problems solved.  Now leave the exposure.  In studio work we tried to use lowest possible ISO setting, and in such case we set our medium formatg digital capture to 50, and this means either we set the Canon or Nikon to the "L" level - and live with some erxtra noise or stop the lens further to compesate - possibly at loss of sharpness.  But a camera like SONY NEX-5, we cannot afford 2 extra stop on apature setting so the only solution will be either a PL or a ND, to help balance it, just as many comsumer or prosumer camcorder with a build-in ND for similar issues, although mostly outdoors.
There was a while when the silver base still and motion photography using the very same media, but with the wake of many broadcast equipment that many camcorder use tape, somehow a departure from the still capture.  Now, with the digital technology, everything come together again.