I want to make pictures in plain daylight (cloudy day) with my Linhof 4x5 but I need to have REALLY long exposure times... (1 hour). I need normal contrast negs for printing... One thought was to expose Ilford ortho film with a red filter. Do you think this would allow me to expose for an hour with say, an f16 or f22 ? I guess the red filter for the ortho film will be much stronger than an ND for a panchromatic one... On the other hand I can put several ND's one on top of the other, but then I risk vignetting (too many screw-on filters) and they will cost me a fortune to buy... I could use an IR filter but I don't know if there will be anything on the film (even if I use a pan film). Are there any more ideas ??