I am in the process of setting up a Durst 138S with condenser head. With a large 500watt bulb I can get a a very even field of light (about .1 stop variation) over the whole 5x7 negative area. But I need to get and hook up a blower to cool this. Since my current goal for this enlarger is to handle 6x17 negatives I decided to see how even the light was with a 150watt bulb. This bulb is much smaller than the 500Watt. I was surprised to see that it has only a 1/3 of a stop fall off over the 6x17 area. At first I decided that this couldn't possibly work. Then I noticed my 4x5 enlarger with the Ilford 500 head and decided to use it as a reference, since I have been happy with the results. I found the corners of the 4x5 image area to have about .5 stops of falloff. I guess that explains why I sometimes need to burn in the corners a bit. So the Durst for 6x17 with the "wrong" bulb is actually more even than what I am used to in 4x5. So who else has measured their enlargers? What were the results? I am using one of the Darkroom Automation meters to take the measurements, but I imagine a handheld camera meter could work as well. Time to see how a few prints come out. I'll try both bulbs.