Hi, The biggest reason I'm thinking of a VND is due to keeping video very close to the same brightness level in different shooting instances. As for portraits, landscapes, etc. I believe that a variety of fixed ND's would be fine, I could always fine tune lighting in Lightroom due to shooting in raw. I'd like to add, I use Sony Vegas Pro for all my video editing.
A couple questions do come to mind; 1)
Would stacking 77mm ND's introduce vignetting? 2)
Are there thin enough ND's that could be stacked without vignetting? 3)
Would you suggest stepping up to a fixed 82mm ND using a 77-82mm step-up ring? I believe that this should allow stacking without the issue of vignetting. The downside would be losing the ability to use my hood.4)
As for fixed ND's, which ones in your opinion are the cleanest/sharpest? Lots of questions I know and I thank all of you for your great help and input. I sincerely appreciate it. Ray