Quote Originally Posted by glbeas
... Just remember that the Finepix may have an IR blocking filter in it and you are using the residual sensitivity through that for a very low EI. ...
Thanks, you're right! The sun is shining so I checked with daylight, and the 87 filter requires about 10 stops more exposure. I'll check the extra exposure needed with my studio and 'camera' flashguns next time i set them up. (I've got some ND filters I can use to reduce the non-IR exposure with)