Quote Originally Posted by tomtom
sandy - is your graph on unblinkingeye for bpf200 rated at 100asa? i sort of used those charts to figure out a development time but i rated my film at 200asa. now i'm not sure if my negs are fine or under developed or exposed :-?

oh well, i'll be rating it at 100asa for now on :-)

tomtom
I have always rated BPF 200 at EI 100 for my testing. You can easily tell if your negatives are under developed. Just look at a shadow area (say about Zone II or III) and see if there is any detail there. If not, it was underexposed. If there is a lot of density in these areas you probably over exposed. Time of development has relatively little impact on shadow detail density so it is important to look her for signs of under or over exposure.

Two others issues with BPF 200, and its sister films Fortepan 200 and JandC 200, is that they have a tremendous amount of development latitude and a relatively low CI at gamma infinity. In other words, you can develop the film over a wide range of times without significantly changing the contrast, or CI. The overall density of the negative increases, of course, but the slope of the curve stays about the same. This is a great feature in some respects because regardless of how long you develop the film you will still have a printable negative.

A less positive way of stating the above is that films that have a lot of development latitude do not respond well to expansion and contraction development.

And finally, it is especially important with this film to make your own tests because I have found different batches to be rather inconsistent in results, especially as regards how much contrast you can get out of the film. I have probably tested FP4+ over fifteen times over the past several years and the results from every tests are virtually identical. Of the eight or so tests I have done with BPF 200 and its sister films the results have been different virtually every time.

Sandy King