What is the thing requiring the NDs. Getting stuck with fast film in bright sunlight? Something else.
Much as I like and enjoy Adrian's voice on the forum, I was puzzled by the comment that NDs darken the viewfinder.
For a given film speed and exposure, any change in the NDs come with a change in T stop. The only thing affecting the brightness of the viewfinder (for most cameras) is film speed and the desired exposure.
Or did I brain fart?