I am trying to make enlarged copy negs from 35mm using a Leitz enlarger and Bergger BPFB-18 copy film. I enlarge the original neg to make an 8x10 positive and then contact print that to make a negative, which is then contact printed onto POP paper. Here's my question -- this film is "blue sensitive." Is it possible using color filters to alter the contrast of the positives and negatives? I have tried using yellow and magenta filters, but they seem to have little effect. Does anyone have experience with this? I would like to change the overall contrast of the 35mm neg to make it more suitable for the POP prints (more or sometimes less contrast), but cannot figure out if there is a way to do this with the color filters. Any suggestions will be much appreciated -- thanks!