I have an Omega D6 with a fan cooled dichroic head (same head as the D5). Is there a maximum time I can leave the enlarger lamp on? I try not to leave the lamp on for more than a minute or two for fear of overheating the head and/or power supply. Am I worried about nothing? I like to play around with cropping and sometimes use an EM-10 exposure meter resulting in some lengthy times with the enlarger lamp turned on. When I did this with my other enlarger (Omega C760) the heat sink would get pretty hot and I would shut it down to cool for a few minutes. The C760 does not have a cooling fan like the D6. It would be nice to know that I have nothing to worry about on my D6. I suspect that this enlarger could easily handle continuous duty but I have erred on the side of caution since I do not want to damage my baby.