Not true about the compensating timer. This is one instance when the timer is NOT in control. I have the head hooked up to the timer and you must still pre-warm the head each time before printing. It's no big deal. I just turn it on at the start of the printing session to get it going. Then afterward all you need to do is hit the switch for the time it takes to write the info on the back of the next sheet of paper. I have the exact settings for each grade given to me by Calumet. Alan Ross was the person who did the calculations. While not exact for all papers,lenses,etc, this info is good enough to get someone in the ballpark instead of fiddling with the dials. I am not home right now or I would put the settings up here. If anyone wants them they can PM me.