Tried out a feature of my Phillips Tri-One enlarger today that is sweet. This particular enlarger uses 3 bulbs, each behind its own narrow band R,G or B filter. Filtration is done by varying the intensity of each bulb individually. This means that you can set the aperture on the enlarger lens, and adjust timing by adjusting the intensity of the light. Comes in handy for using mid f-stops instead of extremes.
Bill
