I bought some Efke 25 120 film on ebay, and am awaiting arrival of Calbe /Classic F09 film developer. If anyone has experince with this combination I would appreciate a good starting point for developing times and dilutions. I'll be trying the 50 and 100 speed Efke films as well so I could use advise on these too. Does halving the concentration, 1/50 to 1/100 for example, require a doubling of the processing times? Thanks for your(posted 8163 days ago)