thanks shooternz...
I just thought of more, but its kinda tricky...
most movie cameras have matte boxes on rails for filters...and you can put filters in several 'slots' of the matte box...and you can raise or lower those filters as needed ...
I've worked on jobs ( sunsets, sunrise etc ) where the camera operator ( dp advising ) used stuff like " nd gradation " filters to sorta keep bright sky down in order to use the F stop for the main stuff being filmed... in other words, with the gradation filter manually raised and lowered in matte box you sorta keep the sky from blowing out at the beginning of the series of shots or the one shot you're trying to get...for me this experience has been just one shot.. not a series...time lapse..just one shot.
But that would work for timelapse too.. so you start with your gray scale GUESS for the overall time ...and use the gradation filter to keep the sky from blowing out at the beginning... and raise it slowly as it gets darker...and eventually remove it totally...I dont think you'd "see" it in the final product if done little by little....
that stuff is really hard to do well... especially manually cause you have to actually BE THERE and do stuff instead of watching football and enjoying BEER THIRTY ! YIPEE !
