My 4x5 homemade pinhole camera has an aperture ratio of f/280 and it takes on average about 15-20 seconds to expose Ilford MGIVRC paper (iso=6) on a sunny 16 day. How does that compare to the speed of wetplates?
Thanks John. This was 4 minutes in bright sun. Collodion's ISO (if you will) is somewhere between .5 and 1 ISO - it all depends on age, mixture, etc.