Diafine and filter factors

[butch]

Late in the game I'm starting to experiment with filters. When shooting HP5 400, Diafine says to rate it at 800. If you were using a filter with a factor of 2, would you set your meter's ASA for 200? Is there a better way? I've experimented with Tri X and I guess the latitude makes it hard for me to judge the effect.

 

[butch]

Thanks, Very helpful.