I have checked in the digitaltruth.com and there is no information about developing Kentmere 400 at ISO 1600 with Ilford HC. So I tried by guessing and I got it. Now I shot a Kantmere 400 at ISO 3200 and the same problem again. No info found about development time. So I need help on guessing how long time should I try as development time now. So using 1+31 Ilford HC 20C at ISO 400 the development time is 8min The same but at ISO 800 the the time is 12.5 min. The same at ISO 1600 the time I guessed and got right is between 18 and 19 min. Now at ISO 3200, how long time would you suggest me to try? I am thinking about between 26min and 29min(???). But if I can get help on think about it would be nice.