Regarding using Harman's DPP, I have a bit of experience at this and can offer you some advice. I rate Harman DPP at ISO 2, and so a lens set to F11 would require, in lightly overcast daylight (such as what I experienced when doing this 2 days ago) an exposure time of 2 seconds. Bulb setting on your shutter, or a lens cap shutter, can accomplish this nicely.

In super bright summer sun, with a larger aperture, you'll need exposure times around 1/15 to 1/2 second, which not many LF shutters can accurately time. So what I do in those cases is either stop down to a very small aperture and use a 1-2 second exposure or use an ND filter to slow down the exposure until I can time it accurately by hand (2-4 second range is ideal, as it's long enough to time accurately and short enough to permit seated, posed portraits with a head brace).