To the crew: I finally have two high-res photos, including this one, uploaded here: http://www.pbase.com/jason_daniel_anderson/gallery/n741sf, as of 7/20. I have a few more good shots, and will post them asap!
N741SF is a McDonnell Douglas 500E (though its registration says it's a 369E), built in 1988. Registered to Aerial Resources, LLC in Chesapeake, VA, doing business as Chesapeake Helicopters and CBH Imaging Resources out of Hampton Roads Executive airport (KPVG).
The pilot hovered for a few minutes over several spots down the length of Canada Pond, while the passenger wrote furiously on his pad or notebook. They made two separate runs. Assuming he was at the midpoint of the pond, that would put him about 250 feet from my window. Helicopters are quite loud at distances of much more than 250 feet. (I'm just saying).