Is the built-in ND filter on the X100F electronic wizardry or something else? If not a physical filter, I'm assuming it's a very low ISO or something similar.
I tried it for the first time on Saturday when shooting a local waterfall. the 1/4 second I could get with f/8 wasn't quite as slow as I wanted, so I gave the ND setting a whirl and achieved a 2 second exposure, all other things equal.
Two images taken in sequence are shown below. The one using ND (and all others where I used it) are noticeably hazy, almost like a fog. I was also shooting with an X-T2 and real ND filter without getting the haze, so it wasn't spray from the waterfall having more time to spread around.
Is this what I should normally expect using ND on the X100F? Curious if others have played with it. With some effort, I can dehaze and add back contrast in post, but it's not ideal.