copyright JimMendenhallPhotos.com 2013 May 6, 2013 Along the Way. flash and time exposure combined with camera movement in some and wind in others create an impressionist display. Exposures from one-half second at iso 6400 to 2.5 seconds at iso 1600 with flash under powered to register but not blow out the highlights. Light cyan/blue patches are from the overcast twilight sky.