It's sooooo impractical but the results are so fun.

The process is to compose, focus, put ND filter on, swap from finder to film body, half-fire the shutter, pull out the dark slide, fully fire the shutter, push in the dark slide, eject the film, rewind the shutter, and go back to the finder.

One brings to mind the common misconception of the young that all physical media (including dad's CDs) is analogue, and that 'digital' refers only to 'computer' data.