In a post reply of August 2013, you mentioned that sometimes, a speed light is not powerful enough to use as a fill flash with neutral density filters. I want to buy a 5 stop Hoya Pro ND 32 to shoot casual portraits outside, wide open. My speedlight is the Nikon SB-700. Do you think that will be powerful enough? Thank you so much! (Oh, the original post: https://fstoppers.com/product/must-have-tool-strobe-users-2607).