I have a Durst 138 enlarger (original version not the later 138S but I don't think that should matter much). My condensers (Latico) include 2x240, 180, a chipped/cracked 160, 130 and 85. I also have the original cold light head. With condensers the illustration for printing 4x5 using a 150 mm lens shows the 240 on top with the 160 in the bottom slot. Since my 160 is chipped/cracked to one side (probably mostly outside the image area) I tried to avoid using it. Instead using the enlarger with the two 240 condensers (the 210-240 mm lens configuration). That however has tended to produce long exposure times (50 seconds to several minutes at f8). I am using graded paper (Oriental Seagull G2-4 and Nuance expo G2-3). So what should I do? 1. Continue to use two 240 condensers in both top and bottom slots with the 150 mm lens. Which is what I did the whole weekend despite the long exposure times. The prints as expected are tack sharp. 2. Use the two 240 condensers with my EL Nikkor 210 (non-Apo) lens. The 150 is giving me good coverage. I am not sure if the 210 would give me an advantage? 3. Use the 160 in the bottom slot (with the 240 in the top slot) with the 150 mm lens as per instruction book illustration. The chip/crack will likely not intrude on the image? 4. Use the 240 in the top with the 180 in the bottom slot with the 150 mm lens. A configuration not illustrated in the instructions for any lens, the 180 seems intended as the top condenser (flipped the other way around) for shorter lenses. I seem able to focus fine with this configuration and light coverage appears grossly OK by visual inspection but I have not printed with this configuration. 5. Use the cold light head? I am using graded paper anyway. The exposure times with the cold light however were also fairly long. Thanks. Sincerely, Hany.