I did a series of tests, and I found that Rastus had some banding issues when you pushed it to 3600dpi. So what I generally do now is just use the photoshop function to convert to a bitmap at 1800dpi and output it at 1800dpi native resolution. I had been doing 1200bitmap to 2400dpi output, but I liked the 1800 native output better. It also looks visually sharper than a 450 dpi bitmap shoved through the Rastus RIP to a 1800dpi bitmap. I found that trying to get the 1800 dpi bitmaps output to 3600 dpi was a hit-or-miss proposition with no gain in the perceived sharpness of the resulting prints. This is for platinum, mind you. If you are doing silver gelatin,you will probably need to fight the Agfa and get a true 2400 or 3600 output.