F-Stop printing treats the paper exposure in the same way as exposure with the camera is treated ie in f stops rather than pure linear times e.g. shutter speeds going up in a non-linear sequence - 1 second, 2 sec 4 sec 8 sec 16 sec rather than 1sec, 2 sec, 3 sec, 4 sec etc. This does seem to be a natural way to deal with the darkroom exposure.

I have only recently bought an RH Designs Stopclock Professional, having previously done the mathematical calcualtions in my head/bit of paper for F-Stop printing - it is best not to actually think of times with the timer but densities. If a print looks too light by say half a stop, the timer will calculate the extra time needed to get an extra half stop density from the base exposure. It sounds a bit complicated but the RH Designs timer ( there may be others) takes all the headache out of the calculations - bets bit of kit I have bought.

Density starts to rule the printing process rather than times. I have found it soo much easier to concentrate on the actual print my printing is faster, better (I say so myself :-) ) and more enjoyable.