As a follow up: The dusk shots were successful. I had exposures as long as 1 second @ f/5.6 that were sharp, shooting at 100 and 200 ISO. Most were in the 1/4 - 1/6 range. Thanks for the advice.
How slow of a shutter speed can I use at dusk with a Phantom 4 PRO for still images? I want to avoid as much noise as possible and shoot at lower ISOs. I am shooting for architects.
Thanks.